This commit introduces the Sled embedded key-value store for keeping
track of user variables on a per-room basis. Extensive changes were
made to the command module to separate concerns and also pass the
database "connection" down the line.
- A new "Context" object was created to hold information and state
needed for command execution (namely the database).
- Database is very simple for now, storing only user variables.
Refactoring later for storing more complicated types.
- State actor moved into Actors struct, in preparation for either
more actors, or ripping the whole thing out entirely.
- Other modules are also more properly separated, notably
the config module is entirely self-contained.
Updates to the latest matrix SDK, which has a new version of olm-sys
(must be dynamically linked at the moment). Also cleans up the
Dockerfile to remove rustup because Void has reached Rust 1.46.0, for
a faster build.