Install script should lowercase all domain names

A new user submitted the following error to the mailing list today when trying to set up Google login on a new Sandcats install:

{"line":"405","file":"oauth_server.js","message":"Error in OAuth Server: redirectUrl (https://example.sandcats.io/setup/user) is not on the same host as the app (https://EXample.sandcats.io/)","time":{"$date":1657666882313},"level":"warn"} Exception while invoking method 'login' Error: Failed to complete OAuth handshake with Google. failed [400] { "error": "redirect_uri_mismatch", "error_description": "Bad Request" } at getTokens (packages/google-oauth/google_server.js:105:7) at Object.getServiceData [as handleOauthRequest] (packages/google-oauth/google_server.js:80:58) at OAuth._requestHandlers.<computed> (packages/oauth2/oauth2_server.js:10:33) at middleware (packages/oauth/oauth_server.js:170:5) at /programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/fiber_pool.js:43:40

The user had registered EXample as his subdomain instead of example, and Google OAuth failed to match that. Attempting to use capital letters with Google OAuth in any way seemed to throw it off. The user ended up reinstalling with the lowercase version of his subdomain.

Note that I do not know if Sandcats deduplicates capitalized and lowercase subdomains in registrations, so I am unsure if the user had to recover the subdomain or if it allowed re-registration, or if it kept the existing keys during the uninstall and reinstall process.

But I think we should adjust the install script to lowercase all domain names and Sandcats subdomains automatically.