Chore: Deprecate plugin variable `studiocmsMinimumVersion`

Currently StudioCMS plugins must define a [`studiocmsMinimumVersion`](https://github.com/withstudiocms/studiocms/blob/7d2ebfb35a77982b31a7edc95bce01223f77cf15/packages/studiocms/src/schemas/plugins/index.ts#L427), We should deprecate this option in favor of relying on plugins dependency restrictions. (e.g. using `peerDependencies`) Note, when deprecating we should remove all internal plugin checks ran within StudioCMS, and just ignore this setting.