internal/pipewire: implement Core::Destroy

This change also implements pending destructible check on Sync. Destruction method should always be implemented as a wrapper of destructible.destroy.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pipewire/pipewire_test.go

@@ -836,6 +836,7 @@ func TestContextErrors(t *testing.T) {
 
 		{"UnexpectedFileCountError", &pipewire.UnexpectedFileCountError{0, -1}, "received -1 files instead of the expected 0"},
 		{"UnacknowledgedProxyError", make(pipewire.UnacknowledgedProxyError, 1<<4), "server did not acknowledge 16 proxies"},
+		{"UnacknowledgedProxyDestructionError", make(pipewire.UnacknowledgedProxyDestructionError, 1<<4), "server did not acknowledge 16 proxy destructions"},
 		{"DanglingFilesError", make(pipewire.DanglingFilesError, 1<<4), "received 16 dangling files"},
 		{"UnexpectedFilesError", pipewire.UnexpectedFilesError(1 << 4), "server message headers claim to have sent more files than actually received"},
 		{"UnexpectedSequenceError", pipewire.UnexpectedSequenceError(1 << 4), "unexpected seq 16"},