[SB][Chips] Reduce padding in the normal icon + text chips.

This is to make the call chip padding & screen record chip padding look
similar (b/397494654). Mostly, this re-writes a few things:
 - Renames the old padding dimen to _legacy
 - Updates the ChipIcon data class to say whether it has embedded
   padding
 - Adds some comments about how paddings work (when I originally wrote
   this CL, I tried to simplify things but ended up making it worse
   because I forgot why the paddings were in certain places)
 - Always apply the minimum width, but make sure the min width uses
   2*padding

Luckily the screenshot tests will show that most chips are unchanged.

Fixes: 397494654
Bug: 364653005
Flag: com.android.systemui.status_bar_chips_modernization
Test: Trigger screen record chip -> verify it has slightly less side
padding
Test: Verify other chips still have the same padding as before

Change-Id: Iab3d4f043f008fdef1a158e37391007afe6630ce