[openvsx-dev] Migrate from webpack to vite

[Thomas Neidhart <thomas.neidhart@xxxxxxxxxxxxxxxxxxxxxx>]

Hi,

I would like to propose that we migrate from webpack to vite for building the webui of openvsx.

The main reasons would be:

 - improved development mode

 - faster build times

I have created a PR to demonstrate how it would look like:

https://github.com/eclipse/openvsx/pull/1399

Normally you would start a dev server using the `yarn run dev` but to keep compatibility with the existing script I decided to reuse the `watch:default` script to run vite in development mode and serve the default app.

Running tsc is optional and is only there to emit errors / warning, no code should be emitted.

Please take a look at the PR and let me know if there are any concerns with this approach.

Imho, using vite would simplify the development of the webui.

Best,

Thomas