Add generic reflection over event names and versions

[50U10FCA7]

Requires #7

Synopsis

At now, codegen machinery expands into non-generic code for handling event::Names and event::Revisions.

Solution

Provide two traits to add generic reflection:

• event::codegen::Meta for internal purposes (checking the name+ver collisions);
• event::reflect::Meta for public API, allowing to reflect over event::Metas.

and one struct:

• event::Meta as a meta information of Event (event::Name and event::Revision)

Checklist

• Created PR:
  • [x] In draft mode
  • [x] Name contains issue reference
  • [x] Has type and k:: labels applied
  • [x] Has assignee
• Before review:
  • [x] Documentation is updated (if required)
  • [x] Tests are updated (if required)
  • [x] Changes conform code style
  • [x] CHANGELOG entry is added (if required)
  • [x] FCM (final commit message) is posted or updated
  • [x] Draft mode is removed
• [x] Review is completed and changes are approved
  • [x] FCM (final commit message) is approved
• Before merge:
  • [x] Milestone is set
  • [x] PR's name and description are correct and up-to-date
  • [x] All temporary labels are removed

[50U10FCA7]

FCM

Add generic reflection over event names and versions (#6)

- add `es::event::reflect::Name` and `es::event::reflect::Revision` in `arcane-core` crate
- replace `es::event::codegen::Reflect` with `es::event::codegen::Meta` in `arcane-core` crate

[50U10FCA7]

Discussed:

• add es::event::reflect module
• add es::event::Meta { name: Name, revision: Revision } struct
• add es::event::reflect::Meta { const META: &'static [Meta] } trait
• expand es::event::reflect::Meta in es::Event, es::event::Revised derive macros
• remove es::event::VersionedNames, es::event::codegen::VersionedNamesIterator

To discuss:

• namings

ack @tyranron

[50U10FCA7]

@tyranron Meta is now represented as separated traits because we need to know the type of event revision (which requires Revisable bound).