feat(astro): Add enabled option to Astro integration options

[Lms24]

This PR adds a top level enabled option to the Astro integration options. This option can be used to globally enable/disable all Sentry features, either for client or server separately or for both sides simultaneously.

• Disabeling either side will avoid the respective SDK code being injected into the bundles.
• If both sides are disabled, source maps will not be generated and uploaded.
• If both or just the server side is disabled, the Sentry middleware won't be added.
• Obviously, this options defaults to true

API:

// astro.config.mjs

export default defineConfig({
  integrations: [
    sentry({
      // disable entirely
      enabled: false,
      // or just one side
      enabled: {
        client: true, // <-- can also be omitted
        server: false,
      }
    }),
  ],
});

closes #9783
ref #9777