Change t3c -M option to take a comma separated list

[ezelkow1]

This reworks the maxmind -M option to take a comma separated list if a user wishes to download multiple databases

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Which Traffic Control components are affected by this PR?

• Traffic Control Cache Config (t3c, formerly ORT)

What is the best way to verify this PR?

Do a t3c run with the -M option and a single URL to check the original use works. Then can re-run with multiple comma separated URLs and check that they all download/update

PR submission checklist

• This PR has tests
• This PR has documentation
• This PR has a CHANGELOG.md entry
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

[codecov]

Codecov Report

Merging #7580 (44c6d3d) into master (2e995e7) will decrease coverage by 2.19%.
The diff coverage is 20.84%.

❗ Current head 44c6d3d differs from pull request most recent head a7853ef. Consider uploading reports for the commit a7853ef to get more accurate results

@@             Coverage Diff              @@
##             master    #7580      +/-   ##
============================================
- Coverage     27.74%   25.55%   -2.19%     
  Complexity       98       98              
============================================
  Files           686      574     -112     
  Lines         78128    74266    -3862     
  Branches         90       90              
============================================
- Hits          21675    18982    -2693     
+ Misses        54396    53390    -1006     
+ Partials       2057     1894     -163     

Flag	Coverage Δ
golib_unit	48.58% <66.07%> (+0.02%)	⬆️
grove_unit	4.60% <ø> (ø)
t3c_unit	5.31% <2.08%> (-0.01%)	⬇️
traffic_monitor_unit	21.35% <ø> (ø)
traffic_ops_unit	23.31% <7.54%> (-0.12%)	⬇️
traffic_stats_unit	10.14% <ø> (ø)
unit_tests	24.35% <17.08%> (-0.06%)	⬇️
v3	?
v4	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cache-config/t3c-apply/config/config.go	0.00% <0.00%> (ø)
cache-config/t3c-apply/t3c-apply.go	0.00% <0.00%> (ø)
cache-config/t3c-apply/torequest/cmd.go	0.00% <0.00%> (ø)
cache-config/t3c-apply/util/util.go	4.82% <0.00%> (ø)
cache-config/t3c-generate/config/config.go	0.83% <0.00%> (-0.06%)	⬇️
...c_ops/traffic_ops_golang/coordinate/coordinates.go	21.32% <3.51%> (-44.03%)	⬇️
cache-config/t3c-generate/cfgfile/wrappers.go	49.45% <50.00%> (+<0.01%)	⬆️
traffic_ops/traffic_ops_golang/api/api.go	30.79% <55.55%> (+0.27%)	⬆️
lib/go-atscfg/parentdotconfig.go	65.76% <64.15%> (-0.48%)	⬇️
lib/go-atscfg/parentabstraction.go	79.47% <100.00%> (-0.53%)	⬇️
... and 4 more

... and 113 files with indirect coverage changes

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[ocket8888]

the new option should be added to the documentation

[ezelkow1]

the new option should be added to the documentation

thanks, added to the t3c-apply docs

[ezelkow1]

Actually I may rework this to take a comma separated list of URLs instead of tacking on another option since some people just want to be able to grab multiple db's at once