validate mod ids completely

[Qubus0]

as per the info by thunderstore, a "full id" would be {namespace}-{name}-{version_number}
I'm not sure what we would call this id, maybe something like "full_name_id"?

the validation does address the composition, but not the elements of that composition. following thunderstore,
namespace and name are are validated with this ^[a-zA-Z0-9_]$ (where _ can only be replaced with space for display purposes)
and the version_number with this ^[0-9]+\.[0-9]+\.[0-9]+$
Godot does have a regex class you can use

Originally posted by @Qubus0 in #51 (review)