[Feature][Pipewire]Pipewire Backend

[bradc6]

This includes both the changes to the cmake files and a new Pipewire backend. Please lmk if there is interest in this PR and I'll clean it up more cause this is a rough cut for sure

[Catty2014]

Kinda good work, however I've found some issues when stopping playback:

*** pw_stream_destroy called from wrong context, check thread and locking: Operation not permitted
*** impl_ext_end_proxy called from wrong context, check thread and locking: Operation not permitted
*** impl_ext_end_proxy called from wrong context, check thread and locking: Operation not permitted
double free or corruption (!prev)

I'm using pipewire1.2.3.

[Catty2014]

Also, the buffer size must be set very high(8192 on my machine) to have a fluent playback (512 is sufficient for SDL2 backend). Maybe performance issue?