Rename sidebar icon

Not sure why it was ever called "rightbar" when by default it's on the
left, but it's a nondescriptive filename nonetheless and doesn't make a
difference whether Refreshed is in ltr or rtl mode, so here's a more
descriptive and relevant filename.

Change-Id: Ic2a7da57cf0acaf1f2577b5705e9cb4363c94b9c