Update OpenAPI3 emitter for shared routes

[tjprescott]

Closes #1198.

• Emit diagnostic if not all routes that are shared are actually marked as such
• Emit diagnostic if common params are inherently incompatible
• Troubleshoot test scenarios for metadata:
  • can make properties optional
  • bubbles up visibility changes to referencers
• Refactor to not alter the program or type graph
• Operation ID heuristic for merged operations
• Additional scenarios?
• Finish implementation for mulitple request body types.
• Finish implementation for multiple response types

[github-actions]

Changes in this PR will be published to the following url to try(check status of TypeSpec Pull Request Try It pipeline for publish status):
Playground: https://cadlplayground.z22.web.core.windows.net/prs/1770/

Website: https://cadlwebsite.z1.web.core.windows.net/prs/1770/

[azure-pipelines]

You can try these changes at https://cadlplayground.z22.web.core.windows.net/prs/1770/

Check the website changes at https://cadlwebsite.z1.web.core.windows.net/prs/1770/

[tjprescott]

@johanste I updated the PR to allow params to differ by location. The key logic that is reflected in the tests occurs in openapi.ts lines 422:465 (validateCommonParameters). Please scrutinize that heavily and let me know if there are other scenarios I should handle or if I'm handling existing ones incorrectly.

[mikekistler]

Is there documentation for how this works?

[markcowl]

This looks good, a couple of suggestions for additional tests

[nguerrera]

Minor comment about sorting. I looked only at the test cases, not the implementation but that was all I found about the test cases.

[mikekistler]

It looks like some operations may be silently discarded if routes are shared.

Playground Example where operation "bar" is silently discarded.

[tjprescott]

New scenario where signatures are not the same, and bar is still lost.

Playground Example 2

bar is not lost here. Foo and bar are combined in the output spec as foo_bar.

[timotheeguerin]

Same comment as on @daviwil PR, parameters should be typed

alias RouteOptions = {
shared?: boolean
}