chore: simplify tools installation and management with mise

[programmer04]

What this PR does / why we need it:

🙇 Please test locally on your machine.

❗ There is a problem with Checks / linters / lint (pull_request_target), because we use workflow from main branch and it uses third_party/go.mod that is removed in this file, so it has to be merged with by-passing and observing on main

Scope

• Get rid of dir third_party and dedicated go.mod for managing tooling and all related Makefile config. Use mise to install delve from the source code (a binary is not provided).
• gotestsum is handled natively
• crd-ref-docs use the same approach for installation as for delve - built from source
• setup-envtest is handled natively
• staticcheck is handled natively
• cleanup leftovers from already removed (see chore(ci): disable exportloopref, loopvar and enable copyloopvar linter #6563) deprecated looppointer linter.

Which issue this PR fixes:

Follow up for #6563

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.7%. Comparing base (35b1374) to head (056aae6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #6564     +/-   ##
=======================================
+ Coverage   69.5%   73.7%   +4.2%     
=======================================
  Files        202     202             
  Lines      25796   25796             
=======================================
+ Hits       17935   19024   +1089     
+ Misses      6853    5750   -1103     
- Partials    1008    1022     +14     

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[czeslavo]

Let's add the experimental setting to the .mise.toml config file so we don't have to set it manually:

[settings]
experimental = true

[programmer04]

I implemented your suggestion @czeslavo and made couple of other improvements, so please check everything again

[pmalek]

Looks good, worked on my machine 🎉

[czeslavo]

🚀