Allow wildcard additional_hostnames, fixes #2391

[rfay]

The Problem/Issue/Bug:

#2391 requests wildcards for additional_hostnames. I experimented with it and it was pretty easy. Here's a PR. It will need to be looked at much more closely later in the release cycle.

How this PR Solves The Problem:

• Add finesse to validation to remove the "*." on front of additional_hostnames.

• Consider whether this is "OK" to go in, since it doesn't work unless using DNS.
• Needs test for wildcard.
• Needs docs
• Prevent simple "*", as that should be invalid. Validators should make sure empty string is not accepted.

Allow *. in validation - everything else seems to work at first blush.

Manual Testing Instructions:

Automated Testing Overview:

• Needs test for wildcard

Related Issue Link(s):

Release/Deployment notes:

[j6s]

I checked out and built your branch locally to test it.

1. Create an empty project (in my case I had an var_dump($_SERVER); in there to check the vars passed to PHP)
2. Add a wildcard hostname (in my case *.ddev-test)
3. Open in browser using different hostnames

Wildcard hostnames now seem to work when online and (as expected) not work when offline. I cannot determine what effects this change has on the rest of ddev but the wildcard part seems to work.

[j6s]

Just out of curiosity I checked the following 2 things as well:

• Wildcard in the middle of a hostname (e.g. foo.*.ddev-test)
  • Does not work, throws up the invalid hostname message. I wouldn't know what usecase would need this over a leading wildcard however
• Only wildcard as additional_hostnames entry
  • This, surprisingly worked and now routes all ddev domains to my project. It may be a good idea to not allow just * as a hostname to prevent accidentally shadowing other projects to easily

Example wildcard only config:

additional_hostnames:
  - '*'