Move comment action out of models package

[lunny]

As title.

[codecov-io]

Codecov Report

Merging #9254 into master will increase coverage by 0.01%.
The diff coverage is 52.42%.

@@            Coverage Diff             @@
##           master    #9254      +/-   ##
==========================================
+ Coverage   41.03%   41.05%   +0.01%     
==========================================
  Files         556      556              
  Lines       72535    72596      +61     
==========================================
+ Hits        29763    29801      +38     
- Misses      39027    39047      +20     
- Partials     3745     3748       +3

Impacted Files	Coverage Δ
services/pull/merge.go	51.11% <0%> (ø)	⬆️
modules/notification/webhook/webhook.go	37.31% <100%> (ø)	⬆️
services/issue/status.go	57.14% <100%> (ø)	⬆️
models/issue_comment.go	42.85% <100%> (ø)	⬆️
modules/notification/base/null.go	64.51% <100%> (ø)	⬆️
modules/notification/notification.go	72.51% <100%> (ø)	⬆️
modules/notification/mail/mail.go	22.38% <100%> (ø)	⬆️
modules/notification/ui/ui.go	74.46% <100%> (ø)	⬆️
models/error.go	32.42% <20%> (-0.25%)	⬇️
models/issue.go	52.18% <36.66%> (+0.07%)	⬆️
... and 4 more

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