In /stacks inconsistent 'kind' value between GET and PATCH methods

Nobody has claimed this yet.

While working on Grace tests for stacks, I noticed that the `resources` defined for the GET method include a `kind` string property that is limited to an enumeration of acceptable strings. However in the PATCH method the `aditionalResources` property of `kind` is simply a string with no enumeration constraints. So it is possible to add a resource of type 'FOO' or a resource of type "NotificatoinEndpiont" (typos in enumerated type).

__Investigating with jq__

Stacks GET enforces an enumeration of TemplateKind

```bash
$ jq '.paths."/stacks".get.responses."200".content."application/json".schema.properties.stacks.items' cloud.json
{
"$ref": "#/components/schemas/Stack"
}

$ jq '.components.schemas.Stack.properties.events.items.properties.resources.items.properties.kind' cloud.json
{
"$ref": "#/components/schemas/TemplateKind"
}

$ jq '.components.schemas.TemplateKind' cloud.json
{
"type": "string",
"enum": [
"Bucket",
"Check",
"CheckDeadman",
"CheckThreshold",
"Dashboard",
"Label",
"NotificationEndpoint",
"NotificationEndpointHTTP",
"NotificationEndpointPagerDuty",
"NotificationEndpointSlack",
"NotificationRule",
"Task",
"Telegraf",
"Variable"
]
}
```
Stacks PATCH however does not have an enum and allows any string value

```bash
$ jq '.paths."/stacks/{stack_id}".patch.requestBody.content."application/json".schema.properties.additionalResources.items.properties.kind' cloud.json
{
"type": "string"
}
```

So the following is possible after PATCH, with no error thrown

```json
"resources": [
...
{
"apiVersion": "influxdata.com/v2alpha1",
"resourceID": "0969493978387000",
"kind": "Label",
"templateMetaName": "unbridled-bardeen-b87002",
"associations": [],
"links": {
"self": "/api/v2/labels/0969493978387000"
}
},
{
"apiVersion": "influxdata.com/v2alpha1",
"resourceID": "62e6b3f530226648",
"kind": "FOO",
"templateMetaName": "exciting-carver-b87000",
"associations": [],
"links": {
"self": "/api/v2/62e6b3f530226648"
}
}
],
```

Start with the OpenAPI schema shown in cloud.json and inspect the GET and PATCH paths for /stacks and /stacks/{stack_id}. Compare the resources.kind and additionalResources.kind definitions with TemplateKind. Done means PATCH rejects values outside the same allowed kind values as GET, with the relevant schema validation checked.

Written by the indexing model from the issue text.