LCA2022 Setup

Update dates and descriptions for LCA2022.
Remove old miniconf proposal types.
Add local timezone to speaker profile.

Build an ephemeral dev container for rego testing

Create a ephemeral dev container to facilitate testing of
populate_inventory. It can be created, tweeked in the admin interface,
files updated in admin's populate_inventory, then redeployed to deal
with those changes.

A branch based one will need to be created to so we can do this work
without polluting the master branch.