Add Origins, HttpInterface, and basic Discord support

[linc]

See: https://nitroporter.org/domain.html#domain-diagram

Features

• Add pull command to retrieve data from an Origin
• Add Discord as inaugural Origin package (pull -> raw data from origin)
• Add Discord as Source package & update docs

Domain Updates

• Add Package as parent to Source, Target, & Postscript
• Add Origin as a Package type
• Add Https as a Storage type
• Add Storage params to every Package type

Maintenance

• Add storageFactory() & refactor the Storage interface
• Add packageFactory()
• Adjust Request() call to use named params
• Add dependency on symfony/http-cllient
• Add ConnectionManager compatibility with Symfony ClientHttpInterface
• Simplify a few method signatures to stop passing Migration for no reason
• Deprecate translateDatabaseConfig() (just use direct config names from now on)

Assumes pull will only be sourced from HTTP APIs (Storage\Https) for simplicity today even though that is likely a faulty long-term assumption; it shouldn't be difficult to extend if/when the time comes.

Note that Origin doesn't use Migration, so it has more property baggage than Source et. al. This may be part of the path to deprecating the Migration object eventually.

[linc]

It's not possible to convert SnowfakeIDs into non-colliding 32-bit int values even on the scale of a single community. We need index renumbering, which will also unblock merging instances.