libfuzz based tests

[prestonvanloon]

Part of #4882

Blocked until rules_go version 0.23 is released.

Tracking issues / blocking requirements:

• Set gc_goopts for all targets in a build bazelbuild/rules_go#2402
• Use build_settings and transitions instead of aspect for cross-compilation bazelbuild/rules_go#2219
• Part of milestone for 0.23 https://github.com/bazelbuild/rules_go/milestone/1

Update: I've managed to find a way to work around the above blockers with a custom go_library.

[codecov]

Codecov Report

Merging #5095 into master will increase coverage by 3.44%.
The diff coverage is 68.46%.

@@            Coverage Diff             @@
##           master    #5095      +/-   ##
==========================================
+ Coverage   40.41%   43.85%   +3.44%     
==========================================
  Files         240      301      +61     
  Lines       21432    25281    +3849     
==========================================
+ Hits         8661    11088    +2427     
- Misses      11110    12341    +1231     
- Partials     1661     1852     +191