Update Go module version to v8

[zrhoffman]

This PR fixes #4380 and fixes #6304 by updating the ATC module path from

trafficcontrol/go.mod

Line 1 in 75c3769

module github.com/apache/trafficcontrol

to

trafficcontrol/go.mod

Line 1 in 1872785

module github.com/apache/trafficcontrol/v8

and updates references to the latest ATC Go module around the repo to reference the v8 version. See the commit messages for the commands used to update files and #4380 (comment) for the motivation for this PR.

Note that this PR does not move any files, because moving files is unnecessary to update the module version.

Once this PR is merged, a message will appear at the top of https://pkg.go.dev/github.com/apache/trafficcontrol like this:

because the latest module will be at https://pkg.go.dev/github.com/apache/trafficcontrol/v8.

---

Which Traffic Control components are affected by this PR?

• Documentation
• Traffic Control Cache Config (T3C, formerly ORT)
• Traffic Control Health Client (tc-health-client)
• Traffic Control Client
• Traffic Monitor
• Traffic Ops
• Traffic Stats
• Grove
• CDN in a Box (Enroller)

What is the best way to verify this PR?

Verify that the 8 non-URL, non-local-path instances of github.com/apache/trafficcontrol/ in the repo that did not have v8/ appended to them. They should stay as-is:

repo=github.com/apache/trafficcontrol/
git ls-files | xargs grep -Fn "$repo" 2>/dev/null | grep -vE "(https://|src/)${repo//./\\.}" | grep -vF "${repo}v8"
blueprints/api.guidelines.md:101:[the ATC library's Alert structure](https://pkg.go.dev/github.com/apache/trafficcontrol/lib/go-tc#Alert).
blueprints/refetch-invalidation.md:291:github.com/apache/trafficcontrol/lib/go-atscfg/regexrevalidatedotconfig_test.go
blueprints/refetch-invalidation.md:298:github.com/apache/trafficcontrol/traffic_ops/traffic_ops_golang/invalidationjobs/invalidationjobs.go
blueprints/refetch-invalidation.md:304:github.com/apache/trafficcontrol/traffic_ops/testing/api/v1/jobs_test.go
blueprints/refetch-invalidation.md:305:github.com/apache/trafficcontrol/traffic_ops/testing/api/v2/jobs_test.go
blueprints/refetch-invalidation.md:306:github.com/apache/trafficcontrol/traffic_ops/testing/api/v3/jobs_test.go
blueprints/refetch-invalidation.md:307:github.com/apache/trafficcontrol/traffic_ops/testing/api/v4/jobs_test.go
CHANGELOG.md:694:- Importing Traffic Ops Go clients via the un-versioned `github.com/apache/trafficcontrol/traffic_ops/client` is now deprecated in favor of versioned import paths e.g. `github.com/apache/trafficcontrol/traffic_ops/v3-client`.

PR submission checklist

• Existing tests are sufficient
• Modified existing 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 #7814 (1872785) into master (a6b2954) will decrease coverage by 33.81%.
Report is 5 commits behind head on master.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master    #7814       +/-   ##
=============================================
- Coverage     65.64%   31.83%   -33.81%     
  Complexity       98       98               
=============================================
  Files           323      717      +394     
  Lines         12827    82718    +69891     
  Branches        965      965               
=============================================
+ Hits           8420    26337    +17917     
- Misses         4048    54216    +50168     
- Partials        359     2165     +1806     

Flag	Coverage Δ
golib_unit	53.56% <ø> (?)
grove_unit	12.02% <ø> (?)
t3c_unit	5.91% <ø> (?)
traffic_monitor_unit	26.44% <ø> (?)
traffic_ops_integration	69.42% <ø> (ø)
traffic_ops_unit	21.62% <ø> (?)
traffic_portal_v2	74.39% <ø> (ø)
traffic_stats_unit	10.78% <ø> (?)
unit_tests	29.16% <ø> (-45.24%)	⬇️
v3	57.79% <ø> (ø)
v4	79.18% <ø> (ø)
v5	78.58% <ø> (ø)

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

Files Changed	Coverage Δ
cache-config/t3c-apply/config/config.go	0.00% <ø> (ø)
cache-config/t3c-apply/torequest/cmd.go	0.00% <ø> (ø)
cache-config/t3c-apply/torequest/torequest.go	5.65% <ø> (ø)
cache-config/t3c-apply/util/gitutil.go	0.00% <ø> (ø)
cache-config/t3c-apply/util/util.go	0.00% <ø> (ø)
cache-config/t3c-check-refs/config/config.go	0.00% <ø> (ø)
cache-config/t3c-check-refs/t3c-check-refs.go	1.78% <ø> (ø)
cache-config/t3c-generate/cfgfile/all.go	51.38% <ø> (-10.69%)	⬇️
cache-config/t3c-generate/cfgfile/routing.go	84.00% <ø> (ø)
cache-config/t3c-generate/cfgfile/sslkeys.go	0.00% <ø> (ø)
... and 100 more

... and 293 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[rimashah25]

Changes LGTM