Procedures: CLI `call` interface

[gefjon]

Design and implement a way to call procedures and await their results from the SpacetimeDB CLI. Note that procedures live at a different HTTP route than reducers (/database/:name/procedure/:name vs /database/:name/call/:name), at least for now. As such, we'll have to decide between:

• spacetime call does some extra work internally to determine whether it's calling a reducer or a procedure, but hides the difference from the user.
• There's a separate subcommand, possibly spacetime procedure, which calls procedures. Attempting to spacetime call a procedure is an error.

[gefjon]

We like the former version, where the same call CLI command can do either. We intend to modify the /v1/database/:name/call/:func route to call either reducers or procedures, at which point this should require only very minimal modifications to the CLI.

[kistz]

another proposal i thought of is adding the commands:

spacetime reducer db name spacetime procedure db name

Then the call is gone and its not ambigous (call would get marked deprecated and removed in 2.0 in that version) :)

Idk lemme know what you think :>