Modify selectors to also be compatible with P2/3
Modify selectors to also be compatible with P2/3

- Testing found that :host-context selectors with attributes after it
(not wrapped by :host()) would result in host-context being ignored completely in P2/3 on Edge
- This also fixes an issue with the --button-rtl rule for h-align on
Firefox

Brightspace/valence-ui-button