Add strict mode

[Chaoba]

This PR adds enhancements to the internal test app that we could run pre-release to make sure we're not leaking perf regressions into production. Specifically:

• Leak Canary was added for memory leak detection
• Strict mode added to detect memory and threading issues
• Test app functionality expanded into testing sdk in the worst possible scenarios: all public apis are called from the main thread
• Fixes for potential perf regressions (which still aren't released into prod)

[codecov]

Codecov Report

Merging #347 into master will increase coverage by 0.28%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #347      +/-   ##
============================================
+ Coverage     56.73%   57.02%   +0.28%     
+ Complexity      491      488       -3     
============================================
  Files           102      101       -1     
  Lines          3190     3153      -37     
  Branches        219      215       -4     
============================================
- Hits           1810     1798      -12     
+ Misses         1293     1268      -25     
  Partials         87       87