Next Breaking Change Candidates

[natsuk4ze]

1. Upgrade min iOS version to 12

With the Xcode update, Flutter's minimum IOS support version has been upgraded to 12. This plugin should follow suit.

2. Upgrade min Android sdk version to 21

The min sdk version supported by this plugin is 21. However, the actual build.gradle is listed at 19.

gal/android/build.gradle

Line 26 in fe9369b

minSdk 19

This is a result of putting off the breaking change. Currently, this plugin can be compiled with Android sdk 19. However, there is no guarantee that all features will work properly under sdk version 21, and we do not intend to support these in the future.
For more clarity, we should upgrade the minSdk in build.gradle to 21.

3. Rename hasAccess and requestAccess

The names hasPermission and requestPermission may be easier to understand.

4. Update GalException.fromCode to GalException.fromPlatformException