API version generated file

[Joerger]

Since the Teleport version in teleport/version.go is not accessible inside teleport/api, this PR adds a generated version.go file to teleport/api.

This is needed for #7155 and #7118. It will also be necessary when the API is officially versioned and released.

Note: depending on the decided upon api versioning strategy, this generated file may end up having a different version than what's in teleport/version.go.

• API versions might not be incremented with every Teleport release
• API versions might become separate from the Teleport version
  • If this strategy is chosen, it may have some effects on Add V4 Roles #7118, so it would be ideal to decide on an API versioning strategy before Add V4 Roles #7118 is released. Otherwise, we should be able to backport a fix.

[nklaassen]

#7118 has merged to master, can you update api/constants/constants.go and remove the temporary Version there, and api/metadata/metadata.go to use the generated value?

[russjones]

Bot.