Fixed accessibility issues with shortcut customizer buttons

The known issues were related to clipping/truncation of text when font
size became too large to fit into fixed width button containers. This is
now addressed by allowing components to use variable dimensions with min
width/height defined, allowing them to take up as much space as is
permitted by their parent.s

This CL also indirectly addresses a talkback issue with disabled buttons - previously when
focused with talkback, disabled buttons did not announce that they were
disabled or a button. This was due to the use of a non-clickable surface
for disabled buttons. The use of clikable/non-clickable surface was
never necessary as ShortcutHelperClickableSurface allows for enabled
parameter to define whether or not a clickable surface is enabled.

Test: manual - try out the accessibility scenarios above and ensure
everything works as expected.
Flag: com.android.systemui.keyboard_shortcut_helper_shortcut_customizer
Fix: 390050558
Fix: 390073679
Fix: 390072395
Fix: 390098828
Fix: 390047758

Change-Id: I06157cc313dadcb05352553aea8b2eccea76d4ef