configuring load balancing per ingress

[ElvinEfendi]

What this PR does / why we need it:
Adds a support for new annotation so that users can configure a load balancing algorithm per ingress.

Which issue this PR fixes *: fixes #1834

Special notes for your reviewer: n/a

[codecov-io]

Codecov Report

Merging #2167 into master will increase coverage by 0.18%.
The diff coverage is 39.28%.

@@            Coverage Diff             @@
##           master    #2167      +/-   ##
==========================================
+ Coverage    36.4%   36.58%   +0.18%     
==========================================
  Files          69       70       +1     
  Lines        4859     4884      +25     
==========================================
+ Hits         1769     1787      +18     
- Misses       2820     2822       +2     
- Partials      270      275       +5

Impacted Files	Coverage Δ
internal/ingress/controller/controller.go	0% <0%> (ø)	⬆️
internal/ingress/types_equals.go	12.67% <0%> (-0.09%)	⬇️
internal/ingress/annotations/loadbalancing/main.go	100% <100%> (ø)
internal/ingress/annotations/annotations.go	80% <100%> (+0.33%)	⬆️
internal/file/bindata.go	43.07% <100%> (ø)	⬆️
internal/ingress/controller/template/template.go	63.28% <21.42%> (+0.53%)	⬆️
internal/watch/file_watcher.go	80.76% <0%> (-3.85%)	⬇️
cmd/nginx/main.go	23.44% <0%> (+2.06%)	⬆️

---

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[ElvinEfendi]

/assign @dcbw

[ElvinEfendi]

/cc @brava-vinh

[k8s-ci-robot]

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[aledbf]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ElvinEfendi

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