refactor(client-presence): Rename ExperimentalPresenceManager to PresenceManager + remove all experimental naming from package

[WillieHabi]

Description

Now that Presence package has been promoted from experimental to alpha, we should rename ExperimentalPresenceManager to just PresenceManager.

This PR completeley removes all 'experimental' naming from the Presence package.

[msfluid-bot]

Code Coverage Summary

↑ packages.framework.presence.src:
Line Coverage Change: 0.03%    Branch Coverage Change: No change

Metric Name	Baseline coverage	PR coverage	Coverage Diff
Branch Coverage	85.18%	85.18%	→ No change
Line Coverage	69.69%	69.72%	↑ 0.03%

---

Baseline commit: 8a75fa9
Baseline build: 307491
Happy Coding!!

Code coverage comparison check passed!!

[msfluid-bot]

⯅ @fluid-example/bundle-size-tests: +245 Bytes

Metric Name	Baseline Size	Compare Size	Size Diff
aqueduct.js	465.5 KB	465.54 KB	⯅ +35 Bytes
azureClient.js	562.82 KB	562.87 KB	⯅ +49 Bytes
connectionState.js	724 Bytes	724 Bytes	■ No change
containerRuntime.js	262.12 KB	262.14 KB	⯅ +14 Bytes
fluidFramework.js	427.12 KB	427.13 KB	⯅ +14 Bytes
loader.js	134.18 KB	134.19 KB	⯅ +14 Bytes
map.js	42.71 KB	42.71 KB	⯅ +7 Bytes
matrix.js	149.84 KB	149.85 KB	⯅ +7 Bytes
odspClient.js	528.61 KB	528.66 KB	⯅ +49 Bytes
odspDriver.js	97.88 KB	97.9 KB	⯅ +21 Bytes
odspPrefetchSnapshot.js	42.81 KB	42.83 KB	⯅ +14 Bytes
sharedString.js	165.77 KB	165.78 KB	⯅ +7 Bytes
sharedTree.js	417.58 KB	417.58 KB	⯅ +7 Bytes
Total Size	3.37 MB	3.37 MB	⯅ +245 Bytes

---

Baseline commit: 8a75fa9

Generated by 🚫 dangerJS against abc5d1f

[github-actions]

🔗 No broken links found! ✅

Your attention to detail is admirable.

linkcheck output

> [email protected] ci:linkcheck /home/runner/work/FluidFramework/FluidFramework/docs
> start-server-and-test ci:start 1313 linkcheck:full

1: starting server using command "npm run ci:start"
and when url "[ 'http://127.0.0.1:1313' ]" is responding with HTTP status code 200
running tests using command "npm run linkcheck:full"


> [email protected] ci:start
> http-server ./public --port 1313 --silent


> [email protected] linkcheck:full
> npm run linkcheck:fast -- --external


> [email protected] linkcheck:fast
> linkcheck http://localhost:1313 --skip-file skipped-urls.txt --external

Crawling...

Stats:
  444350 links
    3418 destination URLs
       2 URLs ignored
       0 warnings
       0 errors

[jason-ha]

ExperimentalPresenceManager name should be kept. Same for ExperimentalPresenceDO.
Also, in general changelog should not be edited.