Convert to signal input

[sysmat]

• angular 21 is out and signal based(https://angular.dev/reference/migrations)

[madebyjeffrey]

In case anyone is interesting, I have updated code-editor (not diff yet?) to use signal based inputs/outputs and added some test cases beforehand to confirm certain behaviour. I haven't done a PR yet because it isn't complete. My overall plans might include signal based forms as well which would limit it to angular 21, which may not be desirable for all.

https://github.com/madebyjeffrey/code-editor