Update SvelteKit preset

[geoffrich]

With the work in #92 the amount of setup needed to deploy SvelteKit to Azure SWA is very minimal. We should make sure the SvelteKit preset in the Azure SWA CLI reflects these defaults to make deployment as painless as possible.

I don't think any work will need to happen in this repo (maybe docs?). Mainly creating this as a reminder to myself.

[geoffrich]

It would also be nice to get SvelteKit as an option on the "create Static Web App" flow via the VS Code extension, but not sure what controls that.

Edit: opened Azure/static-web-apps#1057

[geoffrich]

v0.12 of the extension should support SvelteKit now. Still want to verify.

[geoffrich]

Also might be good to update the README to note that the extension will set this up for you.

[geoffrich]

Anecdotally, when I ran through this setup as part of another issue investigation it didn't set the right values for api_location in the workflow (it set it to .svelte-kit/azure-tmp/api instead of build/server). Need to investigate further.