Consistent schema for plugin capabilities

[CacheMeOwside]

Currently, the PluginCapability types have an inconsistent naming convention, with a mix of resource:action and action:resource. For example, read:content follows action:resource, while email:send follows resource:action.

Renaming capability strings is a breaking change for plugins, and since our plugin ecosystem is still small, this feels like a good time to have a consistent naming convention.

I'd propose picking either resource:action or action:resource and applying it throughout.

I'm happy to open a PR for whichever direction gets consensus.

[BhargavBhandari90]

I agree with @CacheMeOwside. Good catch