Media Kit: Fix/appease various GCC 11 warnings.

PVS V501: redundant checks

There are some more in telnetd and agg but I'm not sure if they are
intentional, the code is so ugly there.

Change-Id: I9cc2bf8a919c3b1d6c68f2ded8622730497b0f91
Reviewed-on: https://review.haiku-os.org/c/1598
Reviewed-by: Stephan Aßmus <superstippi@gmx.de>

Revert the Codec Kit.

All of Barrett's individual reverts have been squashed into this
one commit, save a few actual bugfixes.

Change-Id: Ib0a7d0a841d3ac40b1fca7372c58b7f9229bd1f0

MediaClient: Fix -Werror=set-but-unused

* The error wasn't checked.

media: Remove debug.h, finalize MediaDebug.h

* Funny rust from 0 AD.

MediaClient: Revert debugging edits

* The -a argument ended up in my git commit inadvently,
sorry about that.

MediaConnection: Cleanup after disconnect

MediaClient: Rename IsRunning to IsStarted

MediaClient: Add ClientRegistered callback

MediaClientDefs: Cleanup unneded methods

MediaClient: Remove Preroll and SyncTo

MediaConnection: Review format negotiation mechanism

MediaClient: Remove SetRunMode

MediaClient: IDs should be signed integers

* It's very important to use a negative value to identify
non valid or uninitialized connections. Additionally, it's preferred
to don't interfere with media_kit types as long as the framework use
it in the backend.

MediaClient: Add remaining wiring for input/output functionality

* BufferReceived is renamed HandleBuffer.
* Update doc.
* Implement buffer production private methods.

MediaClient: Remove operator overloding from private class

MediaConnection: Implement auto release

MediaClient: Polish destructors

* Make Release() the only public way to destroy a connection.

MediaClient: Fix style for private methods and other cleanup

* Cleaned up some unneeded callbacks.

Populate media/experimental with future media_kit classes

* Node implementations headers are move into src/kits/media.