instrgen : Almost complete rewrite of instrgen internals, new way of loading and analyzing packages used by whole go program. utilizing toolexec

[pdelewski]

This PR brings:

• utilizes toolexec compiler switch
• rewrites golang runtime for context propagation
• it's much faster
• contains lot of simplifications

[codecov]

Codecov Report

Merging #4058 (7b9adc1) into main (72a4bcb) will increase coverage by 0.0%.
Report is 1 commits behind head on main.
The diff coverage is 79.4%.

❗ Current head 7b9adc1 differs from pull request most recent head 4aa4632. Consider uploading reports for the commit 4aa4632 to get more accurate results

@@          Coverage Diff          @@
##            main   #4058   +/-   ##
=====================================
  Coverage   80.8%   80.9%           
=====================================
  Files        148     147    -1     
  Lines      10238   10304   +66     
=====================================
+ Hits        8281    8337   +56     
- Misses      1819    1823    +4     
- Partials     138     144    +6     

Files	Coverage Δ
instrgen/driver/main.go	75.2% <79.4%> (+3.6%)	⬆️

[MrAlias]

Going to convert this to an actual draft. Please convert back when this is ready for review.