## Why make this change?

- OpenAPI document is needed only when rest is enabled. For
cosmosdb_nosql it is never enabled. So, any attempts to create the
document will always fail. This shows up as a failure in the logs and
has the potential to misguide the actual error that could cause a
failure to start the engine.
- E.g. see below logs from a
[question on
stackoverflow](https://stackoverflow.com/questions/77432995/dataapibuilderexception-while-trying-to-run-swa-start)
> [dataApi] fail: Azure.DataApiBuilder.Service.Startup[0]
> [dataApi]       OpenAPI Documentor initialization failed.
> [dataApi]
Azure.DataApiBuilder.Service.Exceptions.DataApiBuilderException: OpenAPI
description document can't be created when the REST endpoint is disabled
globally.
> [dataApi] at
Azure.DataApiBuilder.Core.Services.OpenApiDocumentor.CreateDocument() in
/_/src/Core/Services/OpenAPI/OpenApiDocumentor.cs:line 108
> [dataApi] at
Azure.DataApiBuilder.Service.Startup.PerformOnConfigChangeAsync(IApplicationBuilder
app) in /_/src/Service/Startup.cs:line 687
> [dataApi] Unable to launch the runtime due to an error.
> [dataApi] Error: Failed to start the engine.
> [dataApi] cd "C:\Users\alexa\source\repos\az-lead\swa-db-connections"
&&
"C:\Users\alexa\.swa\dataApiBuilder\0.9.6-rc\Microsoft.DataApiBuilder.exe"
start -c staticwebapp.database.config.json --no-https-redirect exited
with code 0

- On the surface the above error seems to be due to an OpenApi document
creation failure, but it shouldn't be the case. We still need more
customer logs to understand the issue. This PR is to fix the misguided
logs.

## What is this change?

- Gaurd OpenAPI document creation call with a check for REST is enabled
or not.
- Change the log error to log warning - to avoid misguiding.

## How was this tested?

- Started the engine locally to verify after the change the failure is
gone for CosmosDb_NoSql.

## Sample Request(s)

Before when the engine has successfully started for CosmosDB_NoSql:

![image](https://github.com/Azure/data-api-builder/assets/3513779/9f0f7a59-3c07-4f9c-b002-900fcf6e8bc5)

After:

![image](https://github.com/Azure/data-api-builder/assets/3513779/b54dafca-f7aa-4bd4-a4f2-0a88321d0959)

---------

Co-authored-by: Abhishek  Kumar <[email protected]>

## Why make this change?

This is simply cherry-picking the following PRs before creating the next
stable 0.9 version:

- #1876
- #1821 
- #1854 
- #1851 
- #1872 
- #1868

---------

Co-authored-by: Sean Leonard <[email protected]>
Co-authored-by: Abhishek  Kumar <[email protected]>
Co-authored-by: neeraj-sharma2592 <[email protected]>
Co-authored-by: Neeraj Sharma (from Dev Box) <[email protected]>
Co-authored-by: aaronburtle <[email protected]>