Consider allowing email hints even when smartlock disabled

[samtstern]

We should consider allowing email autofill in the email flow even when smartlock is disabled for actual retrieval/storage of credentials.

Pros:

• We know this increases conversion rates for email flows significantly
• Does not really hurt development

Cons:

• The email hint selector looks like the Google account picker and may be confusing

[SUPERCILEX]

@samtstern I'm in strong favor of doing this, but there's another con you mentioned before: still using smart lock when the developer explicitly said we shouldn't breaks the API contact. However, this use of smart lock isn't related to saving passwords so I think it should be fine.

[samtstern]

Yeah @SUPERCILEX we'd likely have to change the name of the flag

[SUPERCILEX]

@samtstern Hmmmm, this would cause problems for stuff like #200. 😢