Feature Request: Check defaults for <<collection_name>>

[cpt-kuesel]

In my template I wanted to use <<collection_name>> as a default value and only overwrite this variable for specific collections.
PMM does not check the defaults for this and so the builder used the literal "<<collection_name>>" and not the name of the collection.

Just a quick feature request to be able to use <<collection_name>> in a default value for collection templates.

Example in this gist:
https://gist.github.com/cpt-kuesel/ecc370016163fbf2db327f1c5b142749