Improve label component colors, sizes, etc

[gtsiolis]

Problem to solve

Following #9834, the first iteration of the PillLabel component could use some updates to support cases like a smaller size (see #15201 (comment)), new variants like neutral (see #15194), and more.

Proposal

This issue acts as a placeholder for tracking these improvements and the next iteration of the label component.

Designs

TBD (To be discussed)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.