APIInfo refactor

[ocket8888]

This PR renames the api.APIInfo structure commonly used in Traffic Ops to a less stutter-y api.Info. That's going to be the majority of the changes.

The more important ones, though, are those that move the api.Info structure and its methods and NewInfo into their own, separate file, which will make it much easier to deal with moving forward.

Lastly, I added some tests to some things that weren't being tested.

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Which Traffic Control components are affected by this PR?

• Documentation
• Traffic Ops

What is the best way to verify this PR?

Make sure all of the tests pass

PR submission checklist

• This PR has tests
• This PR has documentation
• This PR doesn't need a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY

[codecov]

Codecov Report

Attention: 68 lines in your changes are missing coverage. Please review.

Comparison is base (adea91d) 28.84% compared to head (31c5447) 31.95%.
Report is 2 commits behind head on master.

Files	Patch %	Lines
...fic_ops_golang/deliveryservice/deliveryservices.go	0.00%	12 Missing ⚠️
...fic_ops_golang/deliveryservice/request/requests.go	12.50%	7 Missing ⚠️
...ffic_ops_golang/deliveryservice/servers/servers.go	12.50%	7 Missing ⚠️
traffic_ops/traffic_ops_golang/server/servers.go	0.00%	7 Missing ⚠️
...traffic_ops_golang/cdnfederation/cdnfederations.go	33.33%	4 Missing ⚠️
...ic_ops_golang/invalidationjobs/invalidationjobs.go	0.00%	4 Missing ⚠️
traffic_ops/traffic_ops_golang/api/info.go	98.21%	2 Missing and 1 partial ⚠️
...ffic_ops/traffic_ops_golang/topology/topologies.go	0.00%	3 Missing ⚠️
traffic_ops/traffic_ops_golang/cdni/shared.go	0.00%	2 Missing ⚠️
traffic_ops/traffic_ops_golang/logs/log.go	0.00%	2 Missing ⚠️
... and 15 more

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7902      +/-   ##
============================================
+ Coverage     28.84%   31.95%   +3.11%     
  Complexity       98       98              
============================================
  Files           602      721     +119     
  Lines         77445    82822    +5377     
  Branches         90      970     +880     
============================================
+ Hits          22342    26469    +4127     
- Misses        53012    54203    +1191     
- Partials       2091     2150      +59     

Flag	Coverage Δ
golib_unit	53.85% <ø> (ø)
grove_unit	12.02% <ø> (ø)
t3c_unit	5.88% <ø> (+0.11%)	⬆️
traffic_monitor_unit	25.47% <ø> (ø)
traffic_ops_integration	69.42% <ø> (ø)
traffic_ops_unit	21.93% <72.24%> (+0.29%)	⬆️
traffic_portal_v2	74.37% <ø> (?)
traffic_stats_unit	10.78% <ø> (ø)
unit_tests	29.29% <72.24%> (+3.62%)	⬆️
v3	57.79% <ø> (ø)
v4	79.18% <ø> (ø)
v5	78.58% <ø> (ø)

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