[llvm] [llvm]Add a simple Telemetry framework (PR #102323)

[Alina Sbirlea via llvm-commits]

https://github.com/alinas commented:

I cannot comment on the design of the Telemetry framework itself.
The unit tests look good as far as testing available extension points and providing examples on how to use/extend the framework.

Added comments for cleaning up the documentation.

https://github.com/llvm/llvm-project/pull/102323