[Verified] Backport analytics events

[chriselion]

Proposed change(s)

This backports (some of the) the analytics events changes in

• In-Editor Analytics for inference #4677 (inference)
• [MLA-1540] Training Analytics #4780 (training)
• Add enum for sensor implementations, send in analytics #4871 (sensor type)

Notable changes:

• Training analytics does not contain the python side events (TrainingEnvironmentInitializedEvent and TrainingBehaviorInitializedEvent). This is because the verified package should use the older python library.
• The "ActionSpec" nested fields are the same, but they are generated from a BrainParameters instead.
• The IBuiltInSensor interface can't be added, so determining the enum value is done in an extension method that just checks the possible classes.

Useful links (Github issues, JIRA tickets, ML-Agents forum threads etc.)

https://jira.unity3d.com/browse/MLA-1739

Types of change(s)

• New feature (OK'ed by release management to add in a patch release)

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)

[chriselion]

Just copied from master. This would have caught the fact that I forgot Analytics.meta file.

[surfnerd]

yum yum