* Generate redacted event enums and implement corresponding event structs
* Enable the *EventContent derives to generate redacted events
Most redacted event code is now generated by the *EventContent derive
macro. The exception are any content structs with the custom_redaction
attribute. This leaves implementing up to the user.
* Add redact method to Redaction/CustomEventContent
* Add accessor methods for redacted event enums
* Add RedactedEventContent trait and super traits to match EventContent
This reverts commit 2a91dc1eb7215a762bd2204bc103ef172258d2d9. Also
* Add back type defs and Any*Event enums
* Move EventDeHelper and from_raw_json_value to lib make pub so event_enum! macro can use them and test.
* Fix Any*Event enum deserialization error
* Remove event_content_enum! macro and ruma-events-macros/src/content_enum.rs
* Use serde's IgnoreAny to skip Unknown field's value
* Clean up imports and test names for state_event
