Add support for automated tests in App Distribution

[lfkellogg]

Description

Adding --test-devices and related flags to appdistribution:distribute action. This will trigger the new Automated Tester feature.

Scenarios Tested

• Kick off tests for a release
• Kick off tests async
• Kick off tests with username/password
• Kick off tests with username/password and resource IDs
• Kick off tests with username but not password (error case)
• Kick off tests with username resource but not password resource (error case)
• Kick off tests with username/password resource but not username/password (error case)

Sample Commands

firebase appdistribution:distribute --app <app id> <path> --test-devices <devices>
firebase appdistribution:distribute --app <app id> <path> --test-devices <devices> --test-async
firebase appdistribution:distribute --app <app id> <path> --test-devices <devices> --test-username <user> --test-password <password>
firebase appdistribution:distribute --app <app id> <path> --test-devices <devices> --test-username <user> --test-password <password> --test-username-resource <resource id> --test-password-resource <resource id>

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.40506% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.31%. Comparing base (8e388c1) to head (c1f6d9e).
⚠️ Report is 1301 commits behind head on master.

Files with missing lines	Patch %	Lines
src/appdistribution/options-parser-util.ts	89.13%	3 Missing and 2 partials ⚠️
src/appdistribution/client.ts	94.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6730      +/-   ##
==========================================
+ Coverage   54.25%   54.31%   +0.05%     
==========================================
  Files         347      349       +2     
  Lines       24197    24283      +86     
  Branches     5005     5021      +16     
==========================================
+ Hits        13129    13190      +61     
- Misses       9866     9888      +22     
- Partials     1202     1205       +3     

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[joehan]

Code mostly looks good, with a few small style fixes suggested. However, this change needs an approved API proposal since it changes that public API of the CLI. I have some concerns about the API for this command that would be better discussed there. I couldn't find one at go/firebase-api-tracker - could you link one if I missed it, or start one up?