feat(telemetry): Refactor "telemetry.py" to "telemetry/recording/__init__.py" to unblock further telemetry improvements.

[michaelsafyan]

This is a narrowly focused subset of the telemetry improvements proposed in #320 . As can be seen in pull request #320, making "telemetry" into a package and moving the existing logic into a "recording" sub-package will enable the creation of a "setup" package that is focused on telemetry initialization and wiring.

Once submitted, it will become possible to begin incrementally factoring out some of the "setup"-related files and contributing them (along with associated unit tests) in more narrowly focused updates.

See also #474 for additional motivation and context.

[hangfei]

Why do we name the new package recording?

[hangfei]

Is this a backward compatible change?

[michaelsafyan]

I've converted this to draft, because I had handed off related discussions/work to @aabmass

To answer your questions, though:

• Why rename: because it enables separating out:
  • Logic to write (record) the telemetry
  • Logic to initialize Open Telemetry

It was intended as a factored out piece of:

#320

The move would enable this eventual tree structure:

• telemetry/
  • setup/ <= logic to initialize Open Telemetry
  • recording/ <= logic to write traces

I believe @aabmass has an internal RFC with your team to discuss plans for ADK telemetry in more detail.