enhance(repo)!: add topics field to build env and repo

[ecrupper]

Closes go-vela/community#774

Adds topics to build env and repo object. Dependent on go-vela/types#285

I noticed that we utilize GetRepoForOrg twice in the PostWebhook function even though we do not update the repo object at all between those two calls. Therefore, I decided to remove the second DB call.

I also took the liberty of abstracting repository event handling in our webhook API func. I saw it as very messy and distracting (it's ok to say that because I wrote it)

I wanted to retroactively adjust repos that have been enabled prior to this change by adding a topics setter call to Repo.Topics in the scm/github/webhook.go process functions. The go-github library only has Topics available for events other than push: google/go-github#2742. Once there is another release, we can add this same functionality to push events.

[codecov]

Codecov Report

Merging #807 (e43b59f) into main (f37d973) will decrease coverage by 0.13%.
The diff coverage is 3.88%.

@@            Coverage Diff             @@
##             main     #807      +/-   ##
==========================================
- Coverage   57.91%   57.79%   -0.13%     
==========================================
  Files         263      263              
  Lines       15862    15908      +46     
==========================================
+ Hits         9187     9194       +7     
- Misses       6261     6300      +39     
  Partials      414      414              

Impacted Files	Coverage Δ
api/webhook.go	0.00% <0.00%> (ø)
database/repo/table.go	100.00% <ø> (ø)
scm/github/repo.go	76.42% <100.00%> (+0.05%)	⬆️
scm/github/webhook.go	86.30% <100.00%> (+0.20%)	⬆️

[wass3rw3rk]

thanks