bug(android/engine): Storage permission denied on Android 14.0+

[darcywong00]

          Trying to install from Chrome Downloads, I get a toast from Keyman: "storage request permission was denied. May fail to install key..." 

Originally posted by @mcdurdin in #10133 (comment)

Also noticed in the user testing setup on #10624

Steps to repro

1. On an Android 14.0+ device, download a kmp file in Chrome
2. Go to Chrome --> Downloads
3. Attempt to install the kmp file
4. Observe the toast error

See if these SO threads works

https://stackoverflow.com/questions/77386225/manifest-permission-manage-external-storage-does-not-work-on-android-14

https://stackoverflow.com/questions/72948052/android-13-read-external-storage-permission-still-usable

[darcywong00]

As a workaround, the kmp can still be installed from the Keyman for Android app as "Install from local file"

[darcywong00]

Other Android developer references
data-storage
manage-all-files

[darcywong00]

More notes:
Google recommends using getExternalFilesDir() to access app-specific files from external storage

https://developer.android.com/training/data-storage/app-specific#external-access-files

[darcywong00]

The links on SO don't look promising.
https://stackoverflow.com/a/78065341

The general consensus is that apps can access files they create. And then use Intent.ACTION_OPEN_DOCUMENT to browse to open specific files (which we already do for "Install from local file").

[darcywong00]

Workaround for enabling permission on Android 12.0 (API 31)

Device Settings --> Apps --> Keyman --> files and media --> Allow access to media only

[darcywong00]

Fixed by #11299