Inconsistent initial selection on passphrase keyboard pages

On the multi-page passphrase keyboard, the initially highlighted key differs between the first time a page is shown and every later visit.

To reproduce on master: Options -> BIP39 Passphrase -> Always Ask (Manual), then Options -> Temporary Signer -> `abandon` x11 + `about`. On the "Enter Passphrase" screen, press '>' to cycle through the pages:
- first pass each page is shown with its first character highlighted ('A', '1', ':')
- after wrapping round once every page is shown with the '>' button highlighted

Since each page after the first is only ever reached by pressing '>' and '>' stays selected when you return to a page, it would be more consistent for those pages to start on '>' on their first display too. (The lowercase page is reached without pressing '>', so starting there on 'a' seems right.)

Present since 0.1.35, when the multi-page keyboard was added, and still on master.
The OTP name entry screen uses the same widget and behaves the same way.