Also flip the dependence between json_schema_validator and kicommon,
and create a shared JSON_SCHEMA_VALIDATOR so that we don't have to
copy/paste the schema loading code as much
Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
Pinned packages don't affect available update notification and will not
be updated with "Update All" button. Manual update is still possible but
will trigger a confirmation dialog.
Adds package update available state, package update operation and all
the corresponding logic around it to make updating package to another
version easy.
The json schema for packages implies that kicad min/max version
restriction takes major.minor.patch string but actual logic
only checks major and minor.
This fixes the logic to work with full major.minor.patch tuple.
Additionally the version max logic will substitute missing portions
with 999 for a reasonable default so that say 7.1 is still considered
as >= 7.1.5 when checking for max version.
Reported here
https://forum.kicad.info/t/updating-already-installed-plugins-using-content-manager/35532/5?u=qu1ck
