Update CODEOWNERS file

[GustavoCaso]

What does this PR do?

Update the CODEOWNER files to assign teams better when specific files are modified.

We still have a catch-all * @DataDog/ruby-guild, meaning every team would get a ping for files not specified on the other rules.

Of course we can tweak and improve those rules if we want

Motivation:

Additional Notes:

How to test the change?

For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[codecov-commenter]

Codecov Report

Merging #3143 (f893a1c) into master (cb5fe8a) will not change coverage.
Report is 20 commits behind head on master.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3143   +/-   ##
=======================================
  Coverage   98.16%   98.16%           
=======================================
  Files        1283     1283           
  Lines       73915    73915           
  Branches     3425     3425           
=======================================
  Hits        72558    72558           
  Misses       1357     1357           

see 3 files with indirect coverage changes

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[ekump]

This question is probably outside the scope of this specific PR, but should we rename ext/ since it appears to be a profiling only folder?

[marcotc]

We can't as ext/ is a standard for Ruby gems with native extensions: https://guides.rubygems.org/gems-with-extensions/

[lloeki]

My rationale here is:

• ext being a generic folder for extensions, it should be owned by the guild.
• ext/ddtrace_profiling_loader and ext/ddtrace_profiling_native_extension should be owned by profiling-rb

[lloeki]

That said, currently profiling is the sole user of libdatadog, but that may/should change, therefore I would like to encourage ownership to be split:

• extension code pertaining to profiling should live in its own profiling-owned subdirectories
• extension code pertaining to libdatadog in general should live in guild-owned subdirectories

e.g:

• ddtrace_profiling_loader has no relationship to profiling at all, merely libdatadog. I suggest we rename it to libdatadog_loader and share ownership.
• ddtrace_profiling_native_extension may or may not contain code that pertains only to libdatadog in general. If so, I'd suggest splitting it away in some way and share ownership of the common bits.

[lloeki]

We can't as ext/ is a standard for Ruby gems with native extensions

Note that is is mostly conventional, The directory being ext is not actually technically required, but I would definitely refrain from changing it to anything else!

[ekump]

That said, currently profiling is the sole user of libdatadog, but that may/should change

That's a good point. I think that may change in the not too distant future.

[lloeki]

I am questioning this a bit: while initially developed by tracing automatic injection sounds like a feature that applies to everyone, not just tracing.

[lloeki]

Looks like this file is missing sig ownership

[lloeki]

Added!