Extras: removed extension interfaces and moved methods to components classes because:

- Javadoc for components that implement extension interfaces are useless because they do not include default methods from the extension interface
- GUI builders do not recognize default methods from the extension interface and it is not possible to edit extension properties in GUI builder
- the idea of adding the extension interface to own components can be also achieved by changing superclass of own component

(issue #117)

flatlaf-extras/build.gradle.kts

@@ -40,6 +40,7 @@ tasks {
 			this as StandardJavadocDocletOptions
 			use( true )
 			tags = listOf( "uiDefault", "clientProperty" )
+			addStringOption( "Xdoclint:all,-missing", "-Xdoclint:all,-missing" )
 		}
 		isFailOnError = false
 	}