Make pill @ and matrix.to links behave the same

[toger5]

Another go at: #7550
The idea is to convert all links to matrix.to links.
This sadly breaks pills since they are expecting a local url. So we change all the pill related code to use and expect a matrix to permalink as well.

I wont bother about the tests until we decide, that this is actually the right approach

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Here's what your changelog entry will look like:

✨ Features

• Make pill @ and matrix.to links behave the same (#7559). Contributed by @toger5.

Preview: https://61e7114c58384814d8cb5ac8--matrix-react-sdk.netlify.app
⚠️ Do you trust the author of this PR? Maybe this build will steal your keys or give you malware. Exercise caution. Use test accounts.

[turt2live]

otherwise seems fine - just need to fix the tests.

[turt2live]

I think this is sane

[toger5]

This is not idea:

if (transformed !== href || // for matrix symbols e.g. @user:server.tdl
                    decodeURIComponent(href).match(ELEMENT_URL_PATTERN) || // for https:vector|riot...
                    decodeURIComponent(href).match(MATRIXTO_URL_PATTERN) // for matrix.to
                ) {

but it gets superseded by #7453 anyways.
If we can get #7453 mergeable quick enough it might be best to just skit this pr?

[toger5]

this review: #7559 (review)
was also applied to #7453

[jryans]

If we can get #7453 mergeable quick enough it might be best to just skit this pr?

Sure, seems fine to me.

[toger5]

#7453 is ready to merge so closing this.