[FEATURE] use arity in freebayes module to allow more than two input files

[bpow]

Is your feature request related to a problem? Please describe

BAM input handling in the current nf-code/freebayes module allows for specification of 1 or 2 bam input files (using input_1, input_1_index, input_2 and input_2_index path inputs).

However, this is not a limitation of freebayes, and furthermore nextflow allows path inputs to contain an arbitrary number of individual paths.

Describe the solution you'd like

• specify alignment and alignment_index as path inputs with arity 1..*
• provide these inputs to freebayes

Describe alternatives you've considered

No response

Additional context

No response