fix(devtools): show non-string ApplicationSettings values - #11580

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for.
• You have signed the CLA.
• All existing tests are passing.
• Tests for the changes are included. (The devtools package has no unit-test target yet. See the verification below.)

What is the current behavior?

The devtools Storage panel reads every ApplicationSettings key with ApplicationSettings.getString(key). On Android that's SharedPreferences.getString(), which throws java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String for any key stored with setBoolean or setNumber. As a result, opening Storage fails for any app with a non-string setting (#10513).

What is the new behavior?

ApplicationSettingsKeyValueProvider.getValue tries the string, boolean and number getters in turn and returns the first one that succeeds, as a string. Missing keys still return undefined. Writes are unchanged.

Verification: I ran a one-off Vitest spec against a mocked ApplicationSettings whose getters throw on a type mismatch, the way Android's do. String, boolean and number keys all read back as 'text', 'true' and '2.5', and the missing key stays undefined. The same spec fails without this change. tsc for packages/devtools reports no new errors.

Closes #10513.