[build-tools] Add Appium remote simulator sessions

[sjchmiela]

Why

Appium is one of the industry standards when it comes to interacting with local and remote mobile devices. I think it may be nice to add support for it to EAS Simulator.

How

Added a new EAS function that installs Appium v3, necessary plugin, starts it and exposes its endpoint through ngrok.

The event collection is a bit wonky since we're repeatedly calling Appium endpoint for events, but maybe it's ok. Alternatively we could extend session event collection mechanism to support getEventsAsync, but decided not to do that (see diff).

Test Plan

Tested manually locally. A remote test is going to be better!

[codecov]

Codecov Report

❌ Patch coverage is 61.37566% with 73 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.34%. Comparing base (067c0e5) to head (70eed8a).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...ls/src/steps/functions/startAppiumRemoteSession.ts	38.39%	61 Missing ⚠️
...ckages/build-tools/src/steps/utils/appiumEvents.ts	86.52%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4189      +/-   ##
==========================================
+ Coverage   63.32%   63.34%   +0.02%     
==========================================
  Files        1025     1028       +3     
  Lines       46786    47017     +231     
  Branches     9865     9853      -12     
==========================================
+ Hits        29624    29778     +154     
- Misses      15707    17137    +1430     
+ Partials     1455      102    -1353     

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[github-actions]

⏩ The changelog entry check has been skipped since the "no changelog" label is present.

[szdziedzic]

Appium 3 removed the GET /sessions endpoint. Session discovery now requires GET /appium/sessions, with the server launched using --allow-insecure=*:session_discovery.

As written, every event-collection poll will fail, so no Appium events are uploaded. When max_idle_time_minutes is configured, an actively used session may also be treated as idle and stopped.

Could we update both the endpoint and the Appium launch arguments, and add test assertions for them?