Create interface for internal logging

[fractalwrench]

Goal

Extracts an interface named EmbLogger that will be used for internal logging. I have renamed InternalEmbraceLogger as EmbLoggerImpl for now but am open to naming suggestions. Extracting this code to an interface will make it easier to verify that specific messages are logged during testing. It also opens up the possibility of using a no-op implementation in production builds to save CPU time.

Testing

Relied on existing test coverage.

[bidetofevil]

Phew. Massive and much needed change. LGTM!

[codecov]

Codecov Report

Attention: Patch coverage is 65.85366% with 14 lines in your changes are missing coverage. Please review.

Project coverage is 81.40%. Comparing base (307d284) to head (58417d8).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #828      +/-   ##
==========================================
- Coverage   81.42%   81.40%   -0.02%     
==========================================
  Files         425      426       +1     
  Lines       11358    11358              
  Branches     1689     1689              
==========================================
- Hits         9248     9246       -2     
- Misses       1400     1402       +2     
  Partials      710      710              

Files	Coverage Δ
...android/embracesdk/FlutterInternalInterfaceImpl.kt	91.66% <ø> (ø)
...oid/embracesdk/ReactNativeInternalInterfaceImpl.kt	64.44% <ø> (ø)
...e/android/embracesdk/UnityInternalInterfaceImpl.kt	45.28% <ø> (ø)
...mbrace/android/embracesdk/anr/EmbraceAnrService.kt	94.00% <ø> (ø)
.../embracesdk/anr/detection/BlockedThreadDetector.kt	82.92% <ø> (ø)
...embracesdk/anr/detection/LivenessCheckScheduler.kt	82.25% <ø> (ø)
...id/embracesdk/anr/detection/TargetThreadHandler.kt	80.95% <ø> (ø)
...embracesdk/anr/detection/UnbalancedCallDetector.kt	100.00% <ø> (ø)
...cesdk/anr/ndk/EmbraceNativeThreadSamplerService.kt	87.50% <ø> (ø)
...embracesdk/anr/ndk/NativeThreadSamplerInstaller.kt	63.63% <ø> (ø)
... and 87 more

... and 1 file with indirect coverage changes