Vite with SSL and not committed SNS

[dskloetd]

Steps to run the NNS dapp frontend against mainnet:

1. In /etc/hosts add a line 127.0.0.1 nns.ic0.app
2. Flush DNS cache sudo killall -HUP mDNSResponder (this works on Mac, might be different on other OSes?)
3. From the repo root, create a mainnet config: DFX_NETWORK=mainnet ./config.sh
4. From the frontend directory, run npm ci
5. From the frontend directory, start the dev server: npm run dev -- --port 443 --https --host nns.ic0.app (this may ask for permission to install a custom certificate; this is necessary)
6. In your browser go to https://nns.ic0.app/ and sign in as usual.

Clean up when you're done

1. Restore /etc/hosts
2. Remove the custom root certificate $HOME/.vite-plugin-mkcert/mkcert -uninstall

Steps I took to create the PR

1. Install npm i vite-plugin-mkcert@1.10.1 -D
2. In vite.config.ts add import mkcert from 'vite-plugin-mkcert' and change plugins: [sveltekit()], to plugins: [sveltekit(), mkcert()], and below it add server: { https: true },
3. Changes to allow a non-committed SNS to be visible

https://dfinity.slack.com/archives/C03H6QEPW5D/p1690358000036119?thread_ts=1690309853.741629&cid=C03H6QEPW5D