refactor(build): update library build to API build and remove repo from executor

[ecrupper]

Ref: go-vela/server#1111

Build is nested now, so no need for repo in the executor.

[codecov]

Codecov Report

Attention: Patch coverage is 75.49020% with 25 lines in your changes are missing coverage. Please review.

Project coverage is 57.96%. Comparing base (34d5b49) to head (701cd10).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #576      +/-   ##
==========================================
- Coverage   58.04%   57.96%   -0.08%     
==========================================
  Files         120      120              
  Lines        5031     4996      -35     
==========================================
- Hits         2920     2896      -24     
+ Misses       1909     1898      -11     
  Partials      202      202              

Files	Coverage Δ
api/executor.go	0.00% <ø> (ø)
executor/linux/build.go	75.00% <100.00%> (+0.06%)	⬆️
executor/linux/linux.go	100.00% <ø> (ø)
executor/linux/opts.go	100.00% <100.00%> (ø)
executor/linux/stage.go	79.01% <100.00%> (ø)
executor/local/build.go	75.40% <100.00%> (ø)
executor/local/local.go	100.00% <ø> (ø)
executor/local/opts.go	95.65% <100.00%> (-0.35%)	⬇️
executor/local/service.go	93.44% <100.00%> (ø)
executor/local/stage.go	79.24% <100.00%> (ø)
... and 20 more

[KellyMerrick]

lgtm