host.json schema validation — add OTel specific rules

[anthonychu]

What problem would the feature you're requesting solve? Please describe.

With OTel, users can sometimes configure host.json in a way that is incorrect, such as mixing OTel and App Insights settings.

Describe the solution you'd like

Update host.json schema on schemastore to flag incompatible configurations related to OTel, such as telemetryMode=OpenTelemetry but there's an appInsights section defined with sampling, etc.

Describe alternatives you've considered

Add warnings to the host, which we want to do as well.

@RohitRanjanMS