[Refactor] CombinedStatus and CommitStatus related functions & structs

[6543]

as title

• add limit for pagination on repoGetCombinedStatusByRef
• fix swagger docs

[codecov-io]

Codecov Report

Merging #14026 (d324da9) into master (9e456b5) will decrease coverage by 0.08%.
The diff coverage is 55.76%.

@@            Coverage Diff             @@
##           master   #14026      +/-   ##
==========================================
- Coverage   42.20%   42.12%   -0.09%     
==========================================
  Files         710      711       +1     
  Lines       77295    77302       +7     
==========================================
- Hits        32626    32564      -62     
- Misses      39290    39383      +93     
+ Partials     5379     5355      -24     

Impacted Files	Coverage Δ
modules/convert/convert.go	74.26% <ø> (-1.44%)	⬇️
routers/api/v1/repo/status.go	49.31% <0.00%> (+5.94%)	⬆️
routers/repo/blame.go	0.00% <0.00%> (ø)
routers/repo/commit.go	29.50% <0.00%> (ø)
services/pull/commit_status.go	4.47% <0.00%> (ø)
modules/convert/status.go	50.00% <50.00%> (ø)
routers/repo/pull.go	31.77% <50.00%> (ø)
models/commit_status.go	62.83% <100.00%> (+0.76%)	⬆️
modules/gitgraph/graph_models.go	84.68% <100.00%> (ø)
routers/repo/view.go	38.11% <100.00%> (+0.64%)	⬆️
... and 19 more

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[6543]

I know this pull diff is not clear in the first place, just because it refactor a lot ...

But I tryed to split up tasks I did in seperate commits and name them as they do ...

hope this will help reviewing this

[6543]

@lunny done - good idear "status" is to general