This PR updates @sentry/vite-plugin used in the SvelteKit SDK from version 0.6.x to the latest 2.x version. In line with this change, we now also decoupled the public API of the vite plugin from the SvelteKit SDK public API, meaning we can bump to a higher plugin major version while we stay in the same SDK major version.

Concrete changes:

• We now use DebugId-based sourcemap upload 🎉
• Due to architecture changes in @sentry/vite-plugin, our sentrySvelteKit plugin factory function returns 6 (5x sourcemap, 1x auto instrumentation) plugins instead of previously two. This is because the Vite plugin now consists of several individual plugins.
• We still have to modify source maps a bit before uploading them and all of this should still happen as late as possible. So we still create a customized version of the uploading plugin and return that instead of the original one.
• Also added direct usage of MagicString to inject global values needed during runtime. Previously, I just handed my modified code to the original plugin's transform hook which might have even messed up source maps.
• The new API is a subset of all Sentry Vite plugin options.
  • I'm happy to add more options before merging this PR. I just don't think we need all of them right from the start. As an alternative, we could allow users to pass in arbitrary options and we type them as unknown or something along these lines 🤔

Example usage (showing all available options; all are optional)

sentrySvelteKit({
  autoUploadSourceMaps: true,
  sourceMapsUploadOptions: {
    org: process.env.SENTRY_ORG,
    project: process.env.SENTRY_PROJECT,
    authToken: process.env.SENTRY_AUTH_TOKEN,
    release: {
	    name: '1.0.1',
	    inject: true
    },
    sourcemaps: {
	    assets: ['./build/*/**/*'],
	    ignore: ['**/build/client/**/*'],
	    filesToDeleteAfterUpload: ['./build/**/*.map']
    }
  },
  autoInstrument: true,
  debug: true
}),

closes #9835
closes #8283