feat: move some app model logic to wuttjamaican

previously the "canonical" way to get the model was via
config.get_model() - but now the canonical way is simply app.model

note that for now, even though wuttjamaican provides a default model,
the rattail model does not (yet?) inherit from it. also since
wuttjamaican does not yet support versioning, that feature remains in
rattail only for now.

various legacy things have been deprecated and will warn if used by
other apps.

docs: add some basic docs for typer commands

remove some docs for legacy commands

Move core command logic to `rattail.commands.base`

deprecate `rattail.commands.core` to align with upstream convention

Add wutta wrapper for `short_session()`

and several related tweaks for tests, docs

Massive overhaul of "generate project" feature

previous incarnation was woefully lacking. new feature is much more
extensible. still need to remove old POS integration specifics in
some places.

and a couple of unrelated things that snuck in..

- deprecate `rattail.util.OrderedDict`
- deprecate `rattail.util.import_module_path()`
- deprecate `rattail.util.import_reload()`

Add initial logic for `rattail cleanup` command

will add a cleaner for beaker sessions shortly; more will come later
i'm sure

Add more error handling to datasync; more docs

still trying to isolate a particular problem for one install, to
determine how it can be worked around...

Misc. changes for vendor catalog batch and related features

not very targeted, but all is solid i think..

Add basic Trainwreck handler

with basic docs and tests!

Add support for syncing roles, with users and permissions for each

but only those roles marked for sync. also by default the GlobalRole
is *not* included in the handler's default list, so this still
requires a bit of setup

Add merge-related methods to `PeopleHandler`, plus some docs

also deprecate `get_people_handler()` function