Requires https://github.com/matrix-org/matrix-js-sdk/pull/432 for availability checking.
Changes:
- Redesign the dialog to look more like https://github.com/vector-im/riot-web/issues/3604#issuecomment-299226875
- Attempt to fix wrong password being stored by generating one per SetMxIdDialog (there's no issue tracking this for now, I shall open one if it persists)
- Backwards compatible with servers that don't support register/availability - a spinner will appear the first time a username is checked because server support can only be determined after a request.
- Rate-limited by a 2s debounce
- General style improvements
- Replaces SetDisplayNameDialog with SetMxIdDialog. This new dialog will use InteractiveAuth to authenticate a user with their chosen mxid.
De-scoped:
- style tweaks for the InteractiveAuth in the dialog (capcha) and error message.
- checking for mxid availability
This makes the following changes:
- Improve CountryDropdown by allowing all countries to be displayed at once and using PNGs for performance (trading of quality - the pngs are scaled down from 32px to 25px)
- "I want to sign in with" dropdown to select login method
- MXID login field that suffixes HS domain (whether custom or matrix.org) and prefixes "@"
- Email field which is secretly the same as the username field but with a different placeholder
- No more login flickering when changing ServerConfig (!) fixes https://github.com/vector-im/riot-web/issues/1517
This implements most of the design in https://github.com/vector-im/riot-web/issues/3524 but neglects the phone number login:

This will be updated in another PR to implement desired things:
- Country code visible once a country has been selected (propbably but as a prefix to the phone number input box.
- Use square flags
- Move CountryDropdown above phone input and make it show the full country name when not expanded
- Auto-select country based on IP
Add simple helper to construct version/commit hash urls
var -> let/const and prepend olmVersionString with v for same reason
for both matrix-react-sdk and riot-web, if unknown/local don't do anything
else try to create a link to the commit hash/tag name
Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>