ElementR: fix emoji verification stalling when both ends hit start at…

… the same time (#4004)

* Rust crypto: handle the SAS verifier being replaced

* lint

* make changes from review

* apply changes from code review

* remove useless assertions

* wrap acceptance inside a try-catch, and factor out acceptance into a function

* fix bugs

* we don't actually need the .accept variable

* move setInner to inside SAS class, and rename to replaceInner

* use defer to avoid using a closure

* lint

* prettier

* use the right name

Co-authored-by: Richard van der Hoff <[email protected]>

* combine onChangeCallback with onChange

* apply changes from review

* add test for QR code verification, and try changing order in onChange

* lint

---------

Co-authored-by: Richard van der Hoff <[email protected]>