Allow handling redirects for default domain in the same way it's done with other domains

[acelaya]

Summary

Due to some limitations, setting redirects for default domain does not behave as expected afterwards.

You need to use config options or env vars instead (INVALID_SHORT_URL_REDIRECT_TO, BASE_URL_TO, REGULAR_404_REDIRECT_TO).

We should deprecate that config, create new one with the DEFAULT_ prefix (and probably without the _TO suffix) that acts as fallback for any domain without a specific value, and then make sure the default domain can also have it's own redirects handled as for any other domain.

• INVALID_SHORT_URL_REDIRECT_TO -> DEFAULT_INVALID_SHORT_URL_REDIRECT
• REGULAR_404_REDIRECT_TO -> DEFAULT_REGULAR_404_REDIRECT
• BASE_URL_REDIRECT_TO -> DEFAULT_BASE_URL_REDIRECT

Additionally, the GET /domains endpoint should return a new prop with the default redirects, so that API consumers can know which is going to be the fallback behavior.

Currently, this can be inferred by checking the redirects of the default domain.

{
  "domains": {
    "data": [
      {
        "domain": "string",
        "isDefault": true,
        "redirects": {
          "baseUrlRedirect": "string",
          "regular404Redirect": "string",
          "invalidShortUrlRedirect": "string"
        }
      }
    ],
    "defaultRedirects": {
      "baseUrlRedirect": "string",
      "regular404Redirect": "string",
      "invalidShortUrlRedirect": "string"
    }
  }
}

---

• Allow setting redirects for default domain.
• "Unset" default domain when creating short URLs from the command line (for the API, a middleware is doing it already).
• Set new env vars and deprecate current ones.
• Update list domains endpoint with default redirects.
• Refactor DomainRepository::findDomainsWithout to DomainRepository::findDomains, as it no longer uses the first argument.