Adds a new version of `AdvancementFlow` based on `ApplicationV2`
and implements `SubclassFlow` & `TraitFlow` using it. Adds some
modified rendering for `AdvancementManager` to support either
application version.

The design of `SubclassFlow` remains the same, but `TraitFlow`
has been reworked to use a separated list and display icons
for each trait.

The V2 version of advancement flows are designed to submit on
change, rather than only submitting during the forward process.
This will generally require changes to the coresponding
advancement's application method to handle piecemeal application.
In order to keep everything in the correct state, this also means
that `apply` is called once before the initial rendering of the
flow to give the advancement a chance to populate initial data.

This change involves some modification to the `Advancement` API for
the `apply`, `restore`, `reverse`, and `automaticApplicationValue`
methods:

- `apply`, `restore`, and `reverse` get a new `options` object
- `automatic` option is passed when the automatic application
  process is being applied
- `initial` option is passed when the `apply` method is called
  initially before the flow is first rendered
- `automaticApplicationValue` has been made `async` (this change
  applies when using both V1 or V2 flows)

All of these changes have been made in a way to allow V1 and V2
advancement flows to coexist for a time, but should support future
changes to the advancement manager allowing for grouped flows.