Let users choose which web client to use and on which domain.

[iambeingtracked]

Is your feature request related to a problem? Please describe.
I often get to join some rooms using matrix.to links but i use a self hosted instance of element, which i open in ungoogled-chromium like a web app. For other purposes I use, for example, firefox. When I press the invite link, for instance https://matrix.to/#/#matrix.to:matrix.org, it asks which homeserver to use during preview, where I am free to select any homeserver. But even after selecting my own homeserver pressing "Continue with Element" doesn't throw me to https://element.my.homeserver. It goes to element.io, no matter the homeserver you selected to preview with. And it's not possible to select which instance of element to use.

Describe the solution you'd like
There are two ways to do it. First, the one I like, try to automatically detect if element (or any other web client is hosted on the server used for preview), if it fails, ask the user to specify it for themselves, or continue with element.io (or other instance of element). Second, which I don't like, although it's easier to implement, is to make it possible to select the client by yourself after pressing "Change", next to "Continue with Element".

Describe alternatives you've considered
Copying the link and pasting it into some chat room in the client and there pressing the link, which throws straight into the room.

Additional context
Please, let's not make matrix that centered around vector.im, matrix.org, element.io and matrix.to, please.
Edit: Also, your feature request form is pretty darn good

[t3chguy]

This would be handled by things like element-hq/element-web#16875

[Zocker1999NET]

I see no reason to implement both. You may display the user "We detected your HS recommends my-element.example.com. We will redirect you there" if one is suggested. Else you display "We will forward you to the official hosting of Element. You may choose another hosting.".

Also, this seems to be at least similar to #197