feat: add support for schedules

[jbrockopp]

xref: go-vela/community#538

Part of go-vela/community#772

Dependent on go-vela/sdk-go#233 and go-vela/worker#479

This adds a set of schedule based commands to support the new /api/v1/schedules endpoints:

vela add schedule --org <org> --repo <repo> --schedule <name> --entry <entry>
vela get schedule --org <org> --repo <repo>
vela view schedule --org <org> --repo <repo> --schedule <name>
vela update schedule --org <org> --repo <repo> --schedule <name> --entry <entry>
vela remove schedule --org <org> --repo <repo> --schedule <name>

[codecov]

Codecov Report

Merging #446 (d58ba43) into main (b023c3b) will increase coverage by 0.70%.
The diff coverage is 95.42%.

@@            Coverage Diff             @@
##             main     #446      +/-   ##
==========================================
+ Coverage   85.79%   86.49%   +0.70%     
==========================================
  Files         133      145      +12     
  Lines        5829     6288     +459     
==========================================
+ Hits         5001     5439     +438     
- Misses        680      694      +14     
- Partials      148      155       +7     

Impacted Files	Coverage Δ
command/schedule/remove.go	88.46% <88.46%> (ø)
command/schedule/view.go	88.46% <88.46%> (ø)
command/schedule/get.go	88.88% <88.88%> (ø)
command/schedule/add.go	89.28% <89.28%> (ø)
command/schedule/update.go	89.28% <89.28%> (ø)
action/schedule/add.go	93.33% <93.33%> (ø)
action/schedule/get.go	93.61% <93.61%> (ø)
action/schedule/remove.go	100.00% <100.00%> (ø)
action/schedule/table.go	100.00% <100.00%> (ø)
action/schedule/update.go	100.00% <100.00%> (ø)
... and 2 more

[wass3rw3rk]

lgtm - minor note on some comment language that we probably want to tweak

[plyr4]

nice, just a couple minor tweaks