Migrate compat mode allowed list to DeviceConfig

To test, manually played with 'adb shell device_config'. Examples:

$ adb shell device_config list autofill
$ adb shell device_config delete autofill compat_mode_allowed_packages
$ adb shell device_config list autofill
compat_mode_allowed_packages: not found

$ adb shell device_config put autofill compat_mode_allowed_packages com.android.chrome[url_bar]:com.brave.browser[url_bar]
$ adb shell device_config list autofill
compat_mode_allowed_packages: found, value is com.android.chrome[url_bar]:com.brave.browser[url_bar]
$ adb shell dumpsys autofill
see:
Autofill Compat State:
  User: 0
    com.android.chrome: maxVersionCode=10000000000, urlBarResourceIds=[url_bar]
from device config: com.android.chrome[url_bar]:com.brave.browser[url_bar]

Bug: 194967348
Test: atest CtsAutoFillServiceTestCases
Test: atest com.android.server.autofill.AutofillManagerServiceTest
Change-Id: I775782622adecb42b86de508f502f03039cc34ca