Change BnoC flavour tagging to use GetFlavourTaggingParticles

Change the way that BnoC HLT2 lines save their extra_outputs for flavour tagging to use GetFlavourTaggingParticles like other working groups instead of using custom functions.

I tried to include some comments to explain what needs to be passed to ft_extra_outputs as it can be a bit confusing depending on whether or not the make_BdsToKstzKstzb() function returns just the B-combiner (return line_alg), which is what GetFlavourTaggingParticles wants, or a tuple including the composite particles as well (return [kstar, line_alg])