Update UI configuration

[nikcio]

Proposed changes

This updates the packages and configuration used for the Backoffice UI.

Generally, it wasn't set up in a working way (at least for prettier) and was using outdated versions, which have now been updated.

This updates the eslint setup to use the recommended setup from here: https://typescript-eslint.io/getting-started/legacy-eslint-setup

I've also replaced the a11y eslint rules as it wasn't registered and targeted JSX which isn't in the UI project. Instead, I've added a Lit-specific a11y rule set.

Notes

• I could see that the existing prettier config was set to tab space 2 and I've also added it to the vs-code settings.json but I generally see 4 as the tab spacing in other projects so it should maybe be set to 4 🤷 ?
• If this is merged a npm run lint --fix and npm run format should be run on the project as a whole to align the formatting and fixing the easy eslint rule violations.

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@Infocaster/developers

[D-Inventor]

Hi @nikcio !! I love this contribution. I'm very happy to see this.

As I'm more backend focussed, this is going over my head a little bit. I will share this with a coworker to get a second opinion.

I see you updated the uui library and angularjs types. I know that for both of those, we rely on the version that Umbraco supplies. I need to confirm that Umbraco's supplied versions match with your update before I merge this. (The uui version was based on what U10 supplied, but I never checked for U13)

Thank you for this, I will get back to you, hopefully today.

[nikcio]

@D-Inventor The PR has been updated 😄