scripts: Fix autoswitch BT profile when using filters
If a source filter is used, the BT profile autoswitch does not work because WirePlumber thinks there is always a client capturing audio from it. This patch fixes the issue by recursively walking through the source filters that are linked to the BT loopback source until a stream is found. If a stream is found at the end of the chain, then it switches to HSP/HFP profile, if the stream is not found, the profile stays to A2DP.