Resolves https://github.com/webrecorder/browsertrix/issues/1912
### Changes
- Show support email, if available, in invalid invite error message
- Separate error message for invite email that doesn't match current
user's
Resolves https://github.com/webrecorder/browsertrix/issues/1874
Support for new two-part sign up flow if first admin user is added to org
- If new user, user registers first, then is able to change the org name / slug on following screen
- If existing user, user accepts invite, then is able to change the org name / slug on following screen
- After confirming org slug name, user is taken to dashboard, or error is shown if org name or slug already taken.
- If org name == org id, org name and slug is automatically set to `{Your Name}'s Archive` when first user is registered / accepts invite
- Email templates updated to better reflect new / existing users and not show org name if it is 'unset' (org name == org id internally)
- tests: frontend unit testing for accept + invite screens.
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Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>
Co-authored-by: sua yoo <sua@suayoo.com>
Co-authored-by: sua yoo <sua@webrecorder.org>
Co-authored-by: Henry Wilkinson <henry@wilkinson.graphics>
Co-authored-by: Ilya Kreymer <ikreymer@users.noreply.github.com>
Co-authored-by: Emma Segal-Grossman <hi@emma.cafe>
