[WTF] Migrate The Repository to React 19 & React Native 0.78.2

[LEGIO-SEXTA-FERRATA]

This is no longer a test PR but is supposed to replace this.

[weirdwater]

As demonstrated by the CI test, changing the JSX factory will require a lot of code changes to fix TS errors in (existing) widget code. If it is really necessary to move forward we may need to provide a codemod or something.

[LEGIO-SEXTA-FERRATA]

That's the dilemma now:
I switched the "jsx" config to "react-jsx" which fixed the build errors but then you cannot configure a jsxFactory. 🥲 Which makes the linter complain about the unused declaration in import.

[LEGIO-SEXTA-FERRATA]

And we still have to have the createElement import for a successful build.

[weirdwater]

We probably need to revisit the eslint rules to fix that.

[weirdwater]

Specifically, we need to change the following in the eslint base configs:

{
    "settings": {
        "react": {
            "pragma": "React"
        }
    },
    "rules": {
        /* These need to be modified to just this */
        "no-unused-vars": "warn",
        "@typescript-eslint/no-unused-vars": "warn",
        
        /* This needs to be added */
        "react/react-in-jsx-scope": "off",
    }
}

Explicit React imports for JSX is no longer necessary.

[alihcsumer]

I suppose it is forgotten.