Update System.Diagnostics.DiagnosticSource to 4.7.0

#### What problem would the feature you're requesting solve? Please describe.
Durable Functions intends to add end-to-end tracing support using the W3C protocol for the Mn Azure planning cycle.

#### Describe the solution you'd like
We would like the Azure Functions host to update its version of [System.Diagnostics.DiagnosticsSource](https://www.nuget.org/packages/System.Diagnostics.DiagnosticSource/) from 4.5 to 4.6 or greater (4.7 is the current latest) so that we can take a dependency on it for its support of W3C protocol. We are bound by the version of DiagnosticsSource used by the Functions host since we are an extension, so we would need the host to update its version if we want to also use it.

#### Describe alternatives you've considered
The 4.5 version of DiagnosticsSource currently used by the Functions host can support E2E tracing via W3C, but it requires us to also take a dependency on the Application Insights SDK. This dependency is not desirable for the Durable Task Framework, which currently doesn't have any AI dependency.

#### Additional context
This may be related to https://github.com/Azure/azure-functions-host/issues/4906, which @brettsam is looking at.

Start by locating where the Azure Functions host pins System.Diagnostics.DiagnosticSource and inspect the existing dependency version. Update the host dependency to 4.7.0 or newer, then verify the host still builds and its dependency resolution remains compatible; the issue does not name a specific file or test.

Written by the indexing model from the issue text.