Consider x-ms-client-name when prechecking for duplicate schemas

[daviwil]

This PR fixes an issue that @pakrym identified in a comment for PR #274 which reported that the Cognitive Search spec was reporting a duplicated schema even after a transform was being used to add x-ms-client-name. The change adds a check for x-ms-client-name when grouping schemas by name for deduplication purposes.

I also added an expanded message at @pakrym's request for when a PreCheck/DuplicateSchema error is raised:

ERROR (PreCheck/DuplicateSchema): Duplicate Schema named SearchError -- properties.details.$ref: undefined => "#/components/schemas/schemas:481",x-ms-client-name: "IndexSearchError" => <none> ; This error can be *temporarily* avoided by using the 'modelerfour.lenient-model-deduplication' setting.  NOTE: This setting will be removed in a future version of @autorest/modelerfour; schemas should be updated to fix this issue sooner than that.

The expanded message informs the user about the modelerfour.lenient-model-deduplication setting so that partner teams can turn it on for their specs temporarily before we remove it in a later version.

[azure-pipelines]

You may test this build by running autorest --reset and then either:

---

add --use: to the command line:

autorest --use:http://tinyurl.com/ycu7z9rp ...

---

or use the following in your autorest configuration:

use-extension:
  "@autorest/modelerfour": "http://tinyurl.com/ycu7z9rp" 

---

If this build is good for you, give this comment a thumbs up. (👍)

And you should run autorest --reset again once you're finished testing to remove it.

[azure-pipelines]

You may test this build by running autorest --reset and then either:

---

add --use: to the command line:

autorest --use:http://tinyurl.com/yb8dtssb ...

---

or use the following in your autorest configuration:

use-extension:
  "@autorest/modelerfour": "http://tinyurl.com/yb8dtssb" 

---

If this build is good for you, give this comment a thumbs up. (👍)

And you should run autorest --reset again once you're finished testing to remove it.

[pakrym]

The original version worked.

[daviwil]

Got confirmation from @pakrym that the latest push also works as expected. Merging it!