Automatically focus text input fields

The text input fields in the signup / login (UIA) process do not automatically grab keyboard focus when they appear. So the user must (1) find them on the screen and (2) successfully tap within their bounding box in order for the keyboard to appear. This is annoying and error-prone.

Same thing happens with the post composer.

So the full set of Views that need to be updated includes at least:

• Username enroll (UIA)
• BS-SPEKE password input (UIA)
• BS-SPEKE password repeat (UIA)
• Email enroll request token (UIA)
• Email enroll submit token (UIA)
• Email login request token (UIA)
• Email login submit token (UIA)
• Setup set displayname
• Post composer

Edit: More views that need fixing:

• Group creation - Group name
• Circle creation - Circle name
• Gallery creation - Gallery name
• Invite sheet - User id field
• Settings -> Profile -> Displayname