Allow logging in with the full MXID #1696

Job	Run time
Run `cargo deny` checks	29s
Check schema	4m 23s
Compile test artifacts	4m 5s
Check the frontend for unused dependencies	25s
Check frontend style	33s
Run the frontend test suite	33s
Lint and test OPA policies	9s
Check Rust style	13s
Check syn2mas	13s
Run Clippy	2m 10s
Run test suite with Rust stable (1)	1m 57s
Run test suite with Rust stable (2)	1m 49s
Run test suite with Rust stable (3)	1m 51s
Tests done	1s
	18m 51s

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