enhance(repo): add repo topics to repo object + build environment

[ecrupper]

Part of the effort for go-vela/community#774

Injects repo topics into the environment as well as saves them in the database.

[codecov]

Codecov Report

Merging #285 (1a5e81f) into main (6c72387) will decrease coverage by 0.04%.
The diff coverage is 88.46%.

@@            Coverage Diff             @@
##             main     #285      +/-   ##
==========================================
- Coverage   96.93%   96.90%   -0.04%     
==========================================
  Files          57       57              
  Lines        6303     6329      +26     
==========================================
+ Hits         6110     6133      +23     
- Misses        143      145       +2     
- Partials       50       51       +1     

Impacted Files	Coverage Δ
database/repo.go	98.25% <72.72%> (-1.75%)	⬇️
library/repo.go	100.00% <100.00%> (ø)

[wass3rw3rk]

one minor typo