This removes the need to provide an undocumented launch argument to
enable custom RTMP service configurations to use multitrack encoding
and also provide a custom configuration.
"Enable network optimizations" in the Advanced Settings is referred to
as `NewSocketLoop` in the code. This feature was incompatible with
multitrack video but now works properly. Remove it from the
incompatible settings check.
VAAPI encoders deviate from other encoders (e.g. AMF, NVENC) with
the "profile" setting being an integer instead of a string. With
enhanced broadcasting, "profile" is signalled as a string. Convert
the string-based profile to the appropriate integer-based profile
for VAAPI encoders as a workaround, until VAAPI supports string-based
"profile" (if ever).
