Fixes https://github.com/vector-im/element-web/issues/15559
This isn't exactly perfect as an implementation: if the user refreshes immediately after forgetting then there is a good chance the room re-appears because of the sync accumulator. At the very least this change makes it so in *most* cases the room goes away, which is probably good enough until https://github.com/vector-im/element-web/issues/14038 can be implemented properly.
Turns out a lot of the typescript warnings about improper warnings were correct. TypeScript appears to be pulling in two copies of the js-sdk when we do this, which can lead to type conflicts (or worse: the wrong code entirely). We fix this at the webpack level by explicitly importing from `src`, but some alternative build structures have broken tests because of this - jest ends up pulling in the "wrong" js-sdk, breaking things.
This is commonly requested by deployments with custom setups or those using SSO. Instead of having them all ship the same welcome.html with redirect code in it, we can offer a built-in redirect.
Note that this doesn't actually redirect and instead just replaces the view. This is to make the change less invasive as otherwise it involves changing the routing layers.
Fixes Fallback UIA postmessage interface
Auto-closes SSO UIA tab when the user has completed the flow within it
Error for when auth stage is restarted because it failed
Use replaceState instead of a redirect to strip the loginToken
Put user into the same post-auth flows of E2ESetup
Skip UIA prompt in this post-auth flow, happy path is a server grace period
Queries the homeserver for PSTN protocol support, and if found,
the add-room button on the DM rooms list section opens a context
menu instead with a 'dial pad' option as well as the current 'start chat'
dialog. Entering a number into this and pressing dial performs
a thirdparty user query for the given string and starts a DM with that
user.
