Director::host doesn't fallback to BASE_URL

[emteknetnz]

The host function uses alternate_base_url instead of just calling baseURL() (which itself uses alternative_base_url if it exists). This shoudl be changed so that if a site doesn't have alternate_base_url defined, it will now fall back to using the BASE_URL env variable

PRs

• ENH Also check BASE_URL in host #10155

[emteknetnz]

On further inspection, as noted in the PR, BASE_URL via SS_BASE_URL is already used