feat(site): add alias domain hooks and validate alias domain names

[mrrobot47]

Summary

Adds hooks around alias domain updates so packages that keep per-domain config (auth-command's htpasswd and ACL files) can protect new alias domains before the proxy serves them and clean up after removal. Alias domain names are now validated and blank entries dropped, since they end up in VIRTUAL_HOST and in per-domain proxy file names. Site delete leaves auth cleanup to auth-command's site_cleanup hook.

Changes

• Fire site_alias_domains_updated ($site_url, $domains_to_add, $domains_to_delete) once an alias domain change has been applied.
• Fire site_alias_domains_before_update ($site_url, $domains_to_add) after the input is validated and before docker-compose.yml is dumped, and site_alias_domains_update_failed ($site_url, $domains_to_add) when the update is aborted after that point (a callback or the compose dump throws, or the Let's Encrypt renewal fails and the old containers are restored).
• Trim alias domain lists and drop blank entries on update and on html site create; an update with nothing left to add or delete is refused. The split is shared as EE\Site\Utils\split_alias_domains().
• Add EE\Site\Utils\validate_alias_domains(): only a hostname or *.hostname with labels of letters, digits, - and _ is accepted (a label can't start with - or _, so _wildcard.X can't collide with another site's wildcard files, or end with -), and default / default_admin_tools (the global auth file names) are rejected in any case. The same rule is exposed per name as is_valid_alias_domain(), and the reserved names as is_reserved_proxy_file_name(), for auth-command. ee site update --add-alias-domains and ee site create --type=html --alias-domains exit with an error listing the invalid names before changing anything. Alias domains being deleted aren't checked, so existing invalid ones can still be removed.
• delete_site() no longer removes htpasswd/<site> or the site's auth and whitelist rows; auth-command's site_cleanup hook removes them along with the _wildcard.<site>, alias and _acl files.

Release / merge order

These PRs ship together in one core release:

• fix(nginx-proxy)!: apply wildcard htpasswd and ACL only to *.X hosts dockerfiles#354: new easyengine/nginx-proxy template (needs a new dockerfiles tag)
• feat(auth): support http auth and ip whitelist on wildcard subdomains and alias domains auth-command#57: wildcard and alias domain auth files, alias domain hooks, upgrade migration
• feat(site): add alias domain hooks and validate alias domain names #502: alias domain hooks, alias domain validation, delete cleanup left to auth-command
• fix(site): validate alias domain names on site create site-type-wp#239 and fix(site): validate alias domain names on site create site-type-php#114: alias domain validation on site create

Order:

1. Merge the dockerfiles PR, tag a new dockerfiles release and confirm the new easyengine/nginx-proxy image is on Docker Hub.
2. Merge the site-command, auth-command, site-type-wp and site-type-php PRs close together (nightly and PR CI build dev-develop of every package) and tag each package.
3. In one core release, bump the four package pins and easyengine/nginx-proxy in img-versions.json together.

Why they are coupled:

• auth-command's container migration regenerates every site's auth files on upgrade and needs the new nginx-proxy image in the same release: the old template applies a _wildcard.X file to sibling sites too (e.g. shop.example.com picks up _wildcard.example.com).
• auth-command syncs alias domain auth files from the site_alias_domains_before_update, site_alias_domains_updated and site_alias_domains_update_failed hooks, which only the new site-command fires.
• site-command no longer removes a site's auth files and rows on site delete; auth-command's site_cleanup hook (autoloaded since feat(auth): support http auth and ip whitelist on wildcard subdomains and alias domains auth-command#57) does it.
• site-type-wp and site-type-php call site-command's new split_alias_domains() and validate_alias_domains(), and auth-command its new is_valid_alias_domain() and is_reserved_proxy_file_name(); with an older site-command, they fail with a fatal "undefined function" error.
• The dockerfiles change is breaking for hand-made feat(nginx-proxy): Add wildcard HTTP auth support for WordPress multisite dockerfiles#298-style _wildcard.X files that were also relied on to protect X itself: X now needs its own htpasswd/X (and vhost.d/X_acl) file.

Testing

• Tested on a live EasyEngine 4.12 install with html, php, wp, wp subdir and wp subdom sites, with plain and *. aliases, multiple users, global auth, IP whitelists, alias add/remove, site delete, self-signed SSL and Let's Encrypt.
• PHP 7.4–8.5 lint.