Update to React 18 and MUI 6

[d-perl]

I'd like to start using this for some of our ongoing web GUI work (to hopefully take advantage of your upcoming PVWS integration), and not start off with out-of-date dependencies, so I took the liberty of upgrading them. It only required very minimal changes.

[abigailalexander]

Thanks for the PR! I noticed a few build issues. As well as missing dependencies, the newer rollup doesn't quite work with the existing config. I received this error when trying to build:
Path of Typescript compiler option 'declarationDir' must be located inside the same directory as the Rollup 'file' option.
I did a quick investigation and it seems like this could be solved by changing declarationDir in tsconfig.json to be "dist", and then updating the output directory for the build file to match.
e.g. in package.json, main becomes "dist/index.cjs.js" instead of "dist/cjs/index.js" and likewise for module.

It would definitely be good to move cs-web-lib to react 18 so we can keep up to date.

[abigailalexander]

When attempting to build with npm run rollup, I received errors that these packages are missing. They're used in rollup.config.js.

[d-perl]

Thanks for the review, I didn't notice those issues when building locally, perhaps I still had those settings in my local environment or something - I will look into them and try to add them to the CI too (seeing as that didn't break due to this issue...)

[abigailalexander]

That would be good, thanks. It seems like we only test the build in CI on tag push (when we publish to npm). It would be useful to have that as a check on a normal PR

[d-perl]

I think that the rollup build is fixed now, but I'm not sure how to test it properly - is there a way to run the unit tests against the built module or something?

[abigailalexander]

I'm not sure if there's an easy way to test a build other than importing the built package into a project and using it (which is what I do, with npm run rollup -> npm pack -> then in the new project I npm install the generated .tgz file).

I did this testing with a project locally and encountered errors:

    node_modules/@diamondlightsource/cs-web-lib/dist/esm/index.js:7:8:
      7 │ declare class DTime {
        │         ~~~~~
        ╵         ;

/node_modules/esbuild/lib/main.js:1472
  let error = new Error(text);
              ^

Looking at the dist/cjs/index.js and dist/esm/index.js files generated by the build, you can see their content is wrong. They're type declaration files instead of javascript files. I've pinpointed where it seems that this is coming from.

Other than that it looks good, thanks for adding the build into the CI.

[abigailalexander]

LGTM, all works now. I've merged the PVWS branch into main so it looks like there's a small merge conflict that appeared, but once that's resolved this can be merged in too