Self hosted users feature flag

[nbradbury]

This PR simply adds the "self hosted users" feature flag to our debug settings. To test:

• Me > Debug settings
• Toggle the enable_self_hosted_users checkbox
• Ensure the checkbox state is remembered

[dangermattic]

	2 Warnings
⚠️	Class SelfHostedUsersFeatureConfig is missing tests, but unit-tests-exemption label was set to ignore this.
⚠️	PR is not assigned to a milestone.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21259-0cf9a3e
	Commit	0cf9a3e
	Direct Download	jetpack-prototype-build-pr21259-0cf9a3e.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21259-0cf9a3e
	Commit	0cf9a3e
	Direct Download	wordpress-prototype-build-pr21259-0cf9a3e.apk

Note: Google Login is not supported on these builds.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 40.46%. Comparing base (2210956) to head (0cf9a3e).
Report is 11 commits behind head on trunk.

Files with missing lines	Patch %	Lines
...ndroid/util/config/SelfHostedUsersFeatureConfig.kt	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            trunk   #21259   +/-   ##
=======================================
  Coverage   40.46%   40.46%           
=======================================
  Files        1530     1531    +1     
  Lines       69826    69831    +5     
  Branches    11443    11444    +1     
=======================================
+ Hits        28255    28259    +4     
- Misses      39124    39125    +1     
  Partials     2447     2447           

Flag	Coverage Δ
	40.46% <80.00%> (+<0.01%)	⬆️

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[dcalhoun]

The test plan succeeded for me on a Samsung Galaxy S20. 🚀

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud