SFX and blip players largely remain the same.

For the music player, we now have to implement network streaming
natively, we no longer have a convenient function that did everything
for us. I introduced QNetworkRequest to download the stream in memory
and signal when it's ready to be decoded and played back. The size is
guarded to prevent the client from accidentally downloading terabytes of
audio.

Delete QFutureWatcher, we no longer need it for concurrency. miniaudio
uses a separate audio thread. Network donwloads and communication with
the track name display are handled by Qt signals.

Also, delete an odd "music.txt" feature. Its purpose was specifying
offsets for loops in a text file per track, but it remained obscure and
unused in practice.

Unsupported:

- Large streams, including unbounded ones (radio). We'll need a ring
  buffer for that, and a mechanism to write to it from the network and
  feed it to the audio thread.

- Effect flags: fade in, fade out, sync pos. Ignored.

- Audio device selection.

* Lightly reworked `NetworkManager`
* Added new modules to handle various connection types.
  * TCP
  * WebSocket
* Added general string splitter alias based on Qt version.
* Replaced `lobby_constructed` and `courtroom_constructed`
* Refactored and partially reimplemented the following classes:
  * `AOBlipPlayer`
  * `AOEmotePreview`
  * `AOMusicPlayer`
  * `AOSfxPlayer`
  * `AOTextArea`

* Ported the project to CMake
  * Android and Mac support dropped for the time
being.
  * Tests, BASS and Discord-RPC are now options
* Restructured and reformated the project.
  * Merged `include` and `src`
  * Renamed `resource` to `data`
  * Renamed various files
  * External libraries headers are no longer included in `src`
  * Replaced header guards with #pragma once
  * Multiple refactors (keywords, headers)
  * Added Qt6 compatibility
* Removed various unused functions and headers
* Reworked AOPacket
  * When content is passed to AOPacket, it should be ensured that the content is already decoded.
  * Encoding/decoding are now static methods.
* Fixed various memory leaks
* Removed animation code for AOImage
  * AOImage is always using static images
* Simplified ChatLogPiece