Wear Assist: show login when logged out, scroll first item into view

[jpelgrom]

Summary

Wear Assist changes to address Google's latest nitpicking review failure:

• Update Assist on Wear to automatically open the login screen when logged out, instead of asking the user to close and login, to prevent text being cut off issues
• Add another item at the top of Assist on Wear to allow the pipeline selector to be scrolled into the center of the screen (the first item cannot be scrolled into the center of the screen)

Screenshots

n/a, now more centered possible but contents are the same

Link to pull request in Documentation repository

n/a

Any other notes