Added native implementation to retrieve system theme.

[alexmercerind]

• Package now has plugin interface for Windows added using command:
  • flutter create --template=plugin --platforms=windows --org com.bdlukaa .
• Added SystemTheme class with darkMode and accentColor attributes to access system theme mode & accent colors state. (Also, AccentColor class)
• Code is formatted using flutter dartfmt ..
• This is not a breaking change. I didn't import it to example, you're free to make changes to Dart code the way you want.
• Functionality of added methods/classes is checked.
• The used dependency is not included inside package, but fetched directly on developer's machine through CMake.

Thankyou.

[alexmercerind]

Dismissed by system_theme.