Update login UI messages per UI messages audit

[eloquence]

Status

Ready for review

Description

Part of #53. Makes error messages a bit more consistent and (hopefully) friendly:

• Always use "passphrase", not sometimes "password".
• Use "that won't work" for form submissions that instantly fail validation, followed by the reason
• Use "that didn't work" for form submissions that fail after being sent, followed by actionable advice (use a fresh two-factor code).

Switches the error bar to SecureQLabel as apostrophes were otherwise displayed incorrectly.

Updates the version string as previously discussed here.

Test plan

• Verify that all errors are handled as expected per the screenshots below, including in Qubes.

Checklist

• Tested in Qubes
• No packaging implications

Screenshots

Click to expand

[eloquence]

@ninavizz and I screen-shared this in Qubes (using fancy new Qubes screen-shairng setup ;-) and she has signed off on these changes. We'd like to do a bit more polish on the error bar in future, to give it more breathing room for longer messages, but that can be done post-beta or in a small follow-up PR.