refactor(api): move deployment logic to separate package

[ecrupper]

Based off of #615 #754 #809 #828 and #829

This change continues the refactor efforts initially introduced in the above PR.

This adds a new deployment package to the github.com/go-vela/server/api package.

This contains all the same handlers that existed previously but with each of them within their own file.

I also updated a few of the previous packages in this refactor effort to have a doc.go file.

[codecov]

Codecov Report

Merging #847 (777ede7) into main (3aa414e) will increase coverage by 0.59%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #847      +/-   ##
==========================================
+ Coverage   58.43%   59.02%   +0.59%     
==========================================
  Files         270      269       -1     
  Lines       15636    15479     -157     
==========================================
  Hits         9137     9137              
+ Misses       6075     5918     -157     
  Partials      424      424              

[cognifloyd]

Minor nit - some copy pasta that already existed before this PR.

[cognifloyd]

Suggested change

	// name: deployment
	// description: Name of the org
	// name: deployment
	// description: Number of the deployment