PageBlob_Create： Create Blob in $root container with "/" in blob name, Azurite succes, but server fail with 400

### Which service(blob, file, queue, table) does this issue concern?
blob
### Which version of the Azurite was used?
3.3.0-preview
### Where do you get Azurite? (npm, DockerHub, NuGet, Visual Studio Code Extension)
VS code
### What's the Node.js version?
v10.15.3
### What problem was encountered?
PageBlob_Create： Create Blob in $root container with "/" in blob name, Azurite succes, but server fail with 400
### Steps to reproduce the issue?
Create Blob "Dir1/Blob" in $root container

Server will fail with "HTTP/1.1 400 The requested URI does not represent any resource on the server."
Azurite will success
### Have you found a mitigation/solution?
No

Test case:
```
Test Name: CloudBlobDirectoryValidateInRootContainer
Test FullName: Microsoft.Azure.Storage.Blob.CloudBlobDirectoryTest.CloudBlobDirectoryValidateInRootContainer
Test Source: C:\code\azure-storage-net\Test\ClassLibraryCommon\Blob\CloudBlobDirectoryTest.cs : line 644
Test Outcome: Failed
Test Duration: 0:00:00.2817027

Result StackTrace:
at Microsoft.Azure.Storage.TestHelper.ExpectedException(Action operation, String operationDescription, HttpStatusCode expectedStatusCode, String requestErrorCode) in C:\code\azure-storage-net\Test\ClassLibraryCommon\TestHelper.cs:line 55
at Microsoft.Azure.Storage.Blob.CloudBlobDirectoryTest.CloudBlobDirectoryValidateInRootContainer() in C:\code\azure-storage-net\Test\ClassLibraryCommon\Blob\CloudBlobDirectoryTest.cs:line 657
Result Message: Assert.Fail failed. No Storage exception received while expecting BadRequest: Try to create a CloudBlobDirectory/blob which has a slash in its name in the root container

```
Debug Log:
```
2019-12-17T09:29:18.249Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: BlobStorageContextMiddleware: RequestMethod=PUT RequestURL=http://127.0.0.1/devstoreaccount1/$root/Dir1/Blob1 RequestHeaders:{"x-ms-blob-type":"PageBlob","x-ms-blob-content-length":"0","x-ms-client-request-id":"761f23a9-6e0c-41ad-b876-7da60cc4b6b2","user-agent":"Azure-Storage/11.1.1 (.NET Core; Win32NT 6.2.9200.0)","x-ms-version":"2019-02-02","x-ms-date":"Tue, 17 Dec 2019 09:29:18 GMT","authorization":"SharedKey devstoreaccount1:EK98OdIb3nb1jkQOVnZjDP8k5cSi8ZwRRUnIFtBuxCw=","content-length":"0","host":"127.0.0.1:10000"} ClientIP=127.0.0.1 Protocol=http HTTPVersion=1.1
2019-12-17T09:29:18.250Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: BlobStorageContextMiddleware: Account=devstoreaccount1 Container=$root Blob=Dir1/Blob1
2019-12-17T09:29:18.250Z 4da17c33-257e-43c1-86ab-7a683bb7134e verbose: DispatchMiddleware: Dispatching request...
2019-12-17T09:29:18.252Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: DispatchMiddleware: Operation=PageBlob_Create
2019-12-17T09:29:18.252Z 4da17c33-257e-43c1-86ab-7a683bb7134e verbose: AuthenticationMiddlewareFactory:createAuthenticationMiddleware() Validating authentications.
2019-12-17T09:29:18.252Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: PublicAccessAuthenticator:validate() Start validation against public access.
2019-12-17T09:29:18.253Z 4da17c33-257e-43c1-86ab-7a683bb7134e debug: PublicAccessAuthenticator:validate() Getting account properties...
2019-12-17T09:29:18.253Z 4da17c33-257e-43c1-86ab-7a683bb7134e debug: PublicAccessAuthenticator:validate() Retrieved account name from context: devstoreaccount1, container: $root, blob: Dir1/Blob1
2019-12-17T09:29:18.264Z 4da17c33-257e-43c1-86ab-7a683bb7134e debug: PublicAccessAuthenticator:validate() Skip public access authentication. Cannot get public access type for container $root
2019-12-17T09:29:18.264Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: BlobSharedKeyAuthenticator:validate() Start validation against account shared key authentication.
2019-12-17T09:29:18.265Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: BlobSharedKeyAuthenticator:validate() [STRING TO SIGN]:"PUT\n\n\n\n\n\n\n\n\n\n\n\nx-ms-blob-content-length:0\nx-ms-blob-type:PageBlob\nx-ms-client-request-id:761f23a9-6e0c-41ad-b876-7da60cc4b6b2\nx-ms-date:Tue, 17 Dec 2019 09:29:18 GMT\nx-ms-version:2019-02-02\n/devstoreaccount1/devstoreaccount1/$root/Dir1/Blob1"
2019-12-17T09:29:18.265Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: BlobSharedKeyAuthenticator:validate() Calculated authentication header based on key1: SharedKey devstoreaccount1:EK98OdIb3nb1jkQOVnZjDP8k5cSi8ZwRRUnIFtBuxCw=
2019-12-17T09:29:18.265Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: BlobSharedKeyAuthenticator:validate() Signature 1 matched.
2019-12-17T09:29:18.265Z 4da17c33-257e-43c1-86ab-7a683bb7134e verbose: DeserializerMiddleware: Start deserializing...
2019-12-17T09:29:18.266Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: HandlerMiddleware: DeserializedParameters={"options":{"metadata":{},"requestId":"761f23a9-6e0c-41ad-b876-7da60cc4b6b2","blobHTTPHeaders":{},"leaseAccessConditions":{},"cpkInfo":{},"modifiedAccessConditions":{}},"contentLength":0,"blobContentLength":0,"version":"2019-02-02","blobType":"PageBlob"}
2019-12-17T09:29:18.272Z 4da17c33-257e-43c1-86ab-7a683bb7134e verbose: SerializerMiddleware: Start serializing...
2019-12-17T09:29:18.272Z 4da17c33-257e-43c1-86ab-7a683bb7134e info: EndMiddleware: End response. TotalTimeInMS=23 StatusCode=201 StatusMessage=undefined Headers={"server":"Azurite-Blob/3.3.0-preview","etag":"\"d-OaQFkAnJaJt+hvFx/S0pr5IgVmw\"","last-modified":"Tue, 17 Dec 2019 09:29:18 GMT","x-ms-client-request-id":"761f23a9-6e0c-41ad-b876-7da60cc4b6b2","x-ms-request-id":"4da17c33-257e-43c1-86ab-7a683bb7134e","x-ms-version":"2019-02-02","date":"Tue, 17 Dec 2019 09:29:18 GMT","x-ms-request-server-encrypted":"true"}
2019-12-17T09:29:48.035Z info: AccountDataStore:init() Refresh accounts from environment variable AZURITE_ACCOUNTS with value undefined
2019-12-17T09:29:48.036Z info: AccountDataStore:init() Fallback to default emulator account devstoreaccount1.
2019-12-17T09:30:48.035Z info: AccountDataStore:init() Refresh accounts from environment variable AZURITE_ACCOUNTS with value undefined
2019-12-17T09:30:48.036Z info: AccountDataStore:init() Fallback to default emulator account devstoreaccount1.
```