Make provides a list of identifiers in the schema

[HebaruSan]

Problem

At one point in KSP-CKAN/NetKAN#7600, a confusing error happened because one module had this:

"provides": [ "AIES-Antenna_Patches" ],

And this conflict:

{ "name": "AIES-Antenna-Patches" }

AIES-Antenna-Patches is depended on by a dependency of this module, but since the provides had an underscore, it tried to pull in a conflicting module and got all confused.

Cause

The schema just has provides as a list of strings! But it has to be identifiers to be useful, so this is a missing guardrail that would have helped in this case.

Changes

Now the schema is updated to consider provides a list of identifiers. This will help with validating pull requests; if an element of provides has an invalid format, an error will be raised specifically about that.

[techman83]

Change LGTM. Thanks for your efforts!