Adds Feature Flag for Autofill Service

[cmonfortep]

Task/Issue URL: https://app.asana.com/0/1149059203486286/1209289199349624/f

Description

Adds FFs around Autofill Service. See task for details.

Steps to test this PR

• checkout the branch
• go to AutofillServiceFeature, and remove all InternalAlwaysEnabled (otherwise is not possible to test)

Feature 1

• install the app
• Go to autofill system settings, ensure DuckDuckGo is not listed there
• open the app, go to feature flags internal setting, enable Autofill Service
• restart the app
• Go to autofill system settings, ensure DuckDuckGo is listed there
• Selected DDG

Feature 2

• Perform one test from https://app.asana.com/0/1149059203486286/1209279712661812/f on a native app
• It should not suggest you anything
• open the app, go to feature flags internal setting, enable canUpdateAppToDomainDataset and canMapAppToDomain
• restart the app
• Repeat the test from step 1
• Now you should see some suggestions (since we have enabled mapping between apps and domains)

UI changes

Before	After
!(Upload before screenshot)	(Upload after screenshot)

[cmonfortep]

• Adds Feature Flag for Autofill Service #5567 👈 (View in Graphite)
• Autofill: Implement mapping for appPackages for autofill provider service #5508
• Autofill Service provider - showing suggestions on other apps - internal version #5561
• develop

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