chore: remove larger compile-time cycles

[thecristen]

Scope

Followup to #2903 which finishes the job.

Implementation

Most of this was accomplished by configuring Phoenix with the following in dev:

config :phoenix, :plug_init_mode, :runtime

Most of the rest was deprecating our call_plug macro with an equivalent arrangement which doesn't create compile-time dependencies.

How to test

This should ultimately not change how the application actually works.

• mix xref graph --format cycles --label compile-connected returns No cycles found
• Can deploy this and have all end to end tests passing.

[joshlarson]

I haven't been able to actually run this yet (my internet connection is just not strong enough), but here are a few preliminary suggestions and comments. Nothing blocking so far!