Fix various components

[rock3r]

This PR fixes a number of issues with various components:

1. Link
   • Disabled icons look closer to Swing
   • Use focusOutline modifier instead of custom implementation
   • Remove indication — it must always be null
2. Checkbox
   • Fix outlines size and position to match the SVGs
   • Use global outline size
   • Tweak standalone metric iconTextGap
3. Radio Button
   • Fix outlines to match the SVGs
4. Dropdown
   • State mutation was broken (no focus, etc.)
   • Min size and padding are closer to Swing now
   • Focus ring was missing
   • Now we pretend it's focused when the menu is open (like Swing does)
5. InputField (TextFields and TextAreas)
   • Only show focus outline when undecorated = false

Plus some minor cleanup.