[AnimatedAction] Refine the button UI to address feedback.

Changes
- Update the font to use google-sans-flex with weight 500 for medium. Currently the font falls back to default font as "google-sans-flex-medium" unavailable.
- Update the stroke width. Currently the stroke is clipped in draw() callback, so doubled in width in the custom drawable.
- Other UI tweaks e.g. set max 2-lin, update corner radius and padding to adjust for 2 lines.

Next
- Add more tests in the follow-up cl

Bug: 383567383
Test: atest SmartActionScreenshotTest
Flag: com.android.systemui.notification_animated_actions_treatment
Change-Id: I2457ef51c53ee68ea00b91ed967de17608d1e843