Add galaxy.yml to collection

[andrewroffey]

Adding a galaxy.yml file to the collection would allow users to target the git repository with a requirements.yml file

e.g.

collections:

  - name: 'https://github.com/geerlingguy/ansible-collection-php_roles.git'
    type: 'git'
    version: '1.0.0'

ansible-galaxy fails to install the collection from a git repo if it doesn't have a galaxy.yml file:

ERROR! Neither the collection requirement entry key 'name', nor 'source' point to a concrete resolvable collection artifact. Also 'name' is not an FQCN. A valid collection name must be in the format <namespace>.<collection>. Please make sure that the namespace and the collection name  contain characters from [a-zA-Z0-9_] only.

This would be useful for cases where access to the internet/Galaxy isn't allowed and the user has a locally cloned copy of the Git repo.