fix(android): set project.ext.minSdkVersion for community modules

[tido64]

Description

Test app fails to build when linked with native modules that require older SDK versions. For instance, @react-native-community/slider:

/Users/runner/work/1/s/node_modules/@react-native-community/slider/android/build/intermediates/tmp/manifest/androidTest/debug/manifestMerger7906989633496071019.xml:5:5-74 Error:
	uses-sdk:minSdkVersion 16 cannot be smaller than version 21 declared in library [com.facebook.react:react-native:0.64.3] /Users/runner/.gradle/caches/transforms-3/eaa8686ae9818bf91937afd6b777f393/transformed/jetified-react-native-0.64.3/AndroidManifest.xml as the library might be using APIs not available in 16
	Suggestion: use a compatible library with a minSdk of at most 16,
		or increase this project's minSdk version to at least 21,
		or use tools:overrideLibrary="com.facebook.react" to force usage (may lead to runtime failures)

Most of these modules try to read rootProject.ext.minSdkVersion (and others) before setting a default value. We just need to set them.

Examples:

• @react-native-async-storage/async-storage
• @react-native-community/slider
• @react-native-picker/picker

Platforms affected

• Android
• iOS
• macOS
• Windows

Test plan

Apply the changes directly to microsoft/fluentui-react-native#1159 and verify that it builds locally.

[github-actions]

🎉 This PR is included in version 0.9.13 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀