migrate from com.* to alternatives

[6543]

migrate more com functions to util or replace with fmt replacements ...

• avoid reflections
• report errors

cc @lunny

[codecov-io]

Codecov Report

Merging #14103 (4211fb8) into master (f6bec85) will decrease coverage by 0.00%.
The diff coverage is 27.46%.

@@            Coverage Diff             @@
##           master   #14103      +/-   ##
==========================================
- Coverage   42.34%   42.34%   -0.01%     
==========================================
  Files         726      727       +1     
  Lines       77819    77860      +41     
==========================================
+ Hits        32952    32969      +17     
- Misses      39452    39473      +21     
- Partials     5415     5418       +3     

Impacted Files	Coverage Δ
cmd/serv.go	2.63% <0.00%> (-0.04%)	⬇️
models/branches.go	41.36% <0.00%> (ø)
models/issue_xref.go	61.22% <0.00%> (ø)
models/repo_unit.go	86.48% <0.00%> (ø)
models/user.go	54.40% <0.00%> (ø)
modules/git/repo.go	42.77% <0.00%> (-0.76%)	⬇️
routers/admin/auths.go	35.44% <0.00%> (ø)
routers/admin/emails.go	0.00% <0.00%> (ø)
routers/admin/notice.go	0.00% <0.00%> (ø)
routers/api/v1/utils/hook.go	0.00% <0.00%> (ø)
... and 36 more

---

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[lunny]

migrate more com functions to util or replace with fmt replacements ...

• avoid reflections
• report errors

cc @lunny

Thanks for your hardworking. I sent a nit change request, otherwise LGTM