Schema and Item refactor

Full refactor of ItemBase/Item/Edge/central schema

• Using this in plugins requires changing the local plugin schema + manual testing if everything works
• Now works with pydantic
• Works with minimal changes to code if developer adds edges with Item.add_edge
• Schema now lives in submodule data.schema. Importing from module works (from .data.schema import Account)
• all base functionality is defined on ItemBase, Item only contains properties
• Edges are stored in Item.__edges__[edge_name]. Item.edge_name will just return a list of targets, but should not be editted
• ItemBase private attributes are defined in the metaclass, to prevent PyLance picking them up in class signature
  • note: defining private attributes on Item subclasses still works, example _my_attribute: Optional[str] = PrivateAttr(None)
• Item schema generation for pod is now done on Item, removed duplicate functionality on PodClient and Plugin

Breaking changes

• Item init arguments are now strict, will throw error if arg is not a model field.
• Pydantic does type coercion. PluginRun(id=1234) == PluginRun(id="1234")
• Edge._type is now called Edge.name (required for Pydantic, can be reverted with workaround).
• Item.from_json now only parses properties. This was already the case in practice, as parsing edges was broken.
• Removed unused/unimplemented methods from ItemBase and PodClient. If a plugin uses a method that is missing, method should be re-added
• EdgeList no longer exists
• Local oauth schema is removed, uses central schema oauth now (same fields)