Switch to using separate rapids-logger repo

[vyasr]

Description

This PR removes rmm's logger code in favor of using the rapids-logger repo to which that code was moved. The main material change is that with the latest commit on that repo rmm will dump output to stderr instead of to a file by default, which was the generally requested behavior and also aligns with the rest of RAPIDS's loggers pre-rapids-logger. Nonetheless, I've marked that as a breaking change (also because the rapids-logger code is no longer available from this repository).

Contributes to rapidsai/build-planning#104.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[bdice]

Approving to unblock further work. I did not read the deleted code, just the CMake changes to use an external repo instead of the vendored code.

[bdice]

@vyasr Can you update the RMM README, too?

rmm/README.md

Line 650 in ba35f8e

etc. The default log file is `rmm_log.txt` in the current working directory, but the environment

[vyasr]

@vyasr Can you update the RMM README, too?

rmm/README.md

Line 650 in ba35f8e

etc. The default log file is `rmm_log.txt` in the current working directory, but the environment

Good call, yes.

[vyasr]

/merge