[API] Add more filters to issues search

[6543]

• Add time filter for issue search (since, before)
• Add limit option for paggination
• Add Filter for: Created by User, Assigned to User, Mentioning User

close #12461

[codecov-io]

Codecov Report

Merging #13514 (293482f) into master (b651409) will decrease coverage by 0.00%.
The diff coverage is 59.09%.

@@            Coverage Diff             @@
##           master   #13514      +/-   ##
==========================================
- Coverage   42.24%   42.23%   -0.01%     
==========================================
  Files         697      697              
  Lines       76576    76596      +20     
==========================================
+ Hits        32346    32350       +4     
- Misses      38914    38923       +9     
- Partials     5316     5323       +7     

Impacted Files	Coverage Δ
routers/api/v1/repo/issue.go	50.45% <50.00%> (-0.35%)	⬇️
models/issue.go	56.73% <100.00%> (+0.14%)	⬆️
modules/util/timer.go	42.85% <0.00%> (-42.86%)	⬇️
modules/charset/charset.go	68.53% <0.00%> (-4.50%)	⬇️
services/pull/pull.go	40.78% <0.00%> (-0.50%)	⬇️
modules/queue/workerpool.go	60.81% <0.00%> (+0.81%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b651409...293482f. Read the comment docs.