While running this in production I noticed a number of ghost
processes with all their clients dead before they released the connection,
so let's track them to log it and remove them from clients

Fixes race conditions in limit enforcement by putting worker processes
in a DynamicSupervisor

Sometimes connections died before being released to the pool, resulting
in MatchErrors

This patch refactors gun pooling to use Elixir process registry and
simplifies adapter option insertion.

Having the pool use process registry instead of a GenServer has a number of advantages:
- Simpler code: the initial implementation adds about half the lines of code it deletes
- Concurrency: unlike a GenServer, ETS-based registry can handle multiple checkout/checkin
requests at the same time
- Precise and easy idle connection clousure: current proposal for closing idle connections in
the GenServer-based pool needs to filter through all connections once a minute and compare their
last active time with closing time. With Elixir process registry this can be done
by just using `Process.send_after`/`Process.cancel_timer` in the worker process.
- Lower memory footprint: In my tests `gun-memory-leak` branch uses about 290mb on peak load (250 connections)
and 235mb on idle (5-10 connections). Registry-based pool uses 210mb on idle and 240mb on peak load

AP C2S tests: Make sure you can't use another user's AP id

See merge request pleroma/pleroma!2767

Support for hosts with scheme in MediaProxy whitelist setting

Closes #1922

See merge request pleroma/pleroma!2754

Fix in-db configuration in dev environment

See merge request pleroma/pleroma!2764

[#1940] Reinstated OAuth-less `admin_token` authentication

Closes #1940

See merge request pleroma/pleroma!2760

[#1940] Added `admin_token` param (as `admin_api_params/0`) to existing Admin API OpenAPI operations.

Transmogrifier: filtering weirdness in address fields

Closes #1916

See merge request pleroma/pleroma!2762

Migrate in-db config after updating to Oban 2.0

See merge request pleroma/pleroma!2765

Previously, in-db configuration only worked when `warnings_as_errors`
was disabled because re-compiling scrubbers on application restart
created a warning about module conflicts. This patch fixes that
by enabling `ignore_module_conflict` option of the compiler at runtime,
and enables `warnings_as_errors` in prod since there is no reason
to keep it disabled anymore.

[#1940] Applied rate limit for requests with bad `admin_token`. Added doc warnings on `admin_token` setting.

[#1940] Reinstated OAuth-less `admin_token` authentication. Refactored UserIsAdminPlug (freed from checking admin scopes presence).

Config/Docs: Expand behaviour suggestions modules at runtime

Closes #1941

See merge request pleroma/pleroma!2755

user: Add support for custom emojis in profile fields

See merge request pleroma/pleroma!2741

Improve database config migration and add documentation

See merge request pleroma/pleroma!2756

Update types for :headers and :options settings in Pleroma.Web.MediaProxy.Invalidation.Http

See merge request pleroma/pleroma!2735

ActivityPub: Don't rename a clashing nickname with the same ap id.

Closes #1937

See merge request pleroma/pleroma!2748

added deprecation warning about using bare domains

Add Pleroma.Upload.Filter.Exiftool

Closes #1935

See merge request pleroma/pleroma!2744