WIP: Towards migration to Svelte 4

[wtcross]

Thank you for this awesome Svelte wrapper for AG Grid. I saw you have a WIP svelte4 branch that was very close to working. I added a few commits on top of yours to get everything working.

Right now tests pass and I have been able to use this version in a Svelte 4 project, but there are a few issues caught by type-aware linting:

ag-grid-svelte\src\lib\AgGridSvelte.svelte
    3:62  error  Avoid referencing unbound methods which may cause unintentional scoping of `this`.
If your function does not access `this`, you can annotate it with `this: void`, or consider using an arrow function instead  @typescript-eslint/unbound-method
    4:61  error  Avoid referencing unbound methods which may cause unintentional scoping of `this`.
If your function does not access `this`, you can annotate it with `this: void`, or consider using an arrow function instead  @typescript-eslint/unbound-method
  372:26  error  Avoid referencing unbound methods which may cause unintentional scoping of `this`.
If your function does not access `this`, you can annotate it with `this: void`, or consider using an arrow function instead  @typescript-eslint/unbound-method

ag-grid-svelte\src\lib\SvelteFrameworkComponentWrapper.ts
  72:5   error  Unsafe return of an `any` typed value                                   @typescript-eslint/no-unsafe-return
  73:7   error  Unsafe call of an `any` typed value                                     @typescript-eslint/no-unsafe-call
  73:13  error  Unsafe member access .prototype on an `any` value                       @typescript-eslint/no-unsafe-member-access
  74:60  error  Unsafe argument of type `any` assigned to a parameter of type `Object`  @typescript-eslint/no-unsafe-argument

ag-grid-svelte\src\routes\guide\02-columns\09-column-spanning\column-spanning-complex.svelte
  81:24  error  Unsafe member access .section on an `any` value  @typescript-eslint/no-unsafe-member-access
  85:24  error  Unsafe member access .section on an `any` value  @typescript-eslint/no-unsafe-member-access

ag-grid-svelte\src\routes\guide\03-rows\01-row-ids\get-row-id.svelte
  22:46  error  Unsafe return of an `any` typed value       @typescript-eslint/no-unsafe-return
  22:58  error  Unsafe member access .id on an `any` value  @typescript-eslint/no-unsafe-member-access

I wanted to get direction from you on how you'd like to resolve these errors. I am guessing this is where you stopped your work on the svelte4 branch. It has been a long time since I worked with Typescript, but it appears that resolving these issues will take some work.

What do you think?