Add args section in meta.yml

[arnaudbore]

Description of feature

As discussed in the slack thread

In @jfy133 words:

We need a new section for listing each args (2, 3, 4) with the sole(?) metadata
for each one is simply the tool of the pipe it is effecting.

In @mirpedrol words:

We want an extra section in the meta.yml to describe the ext.args values.
At the level of tools , inputs and outputs.

It would look like this:

tools:
  - "bcftools":
      description: "..."
      homepage: ...
      args_id: "$args"
      identifier: biotools:bcftools
  - "bcftools plugin setGT":
      description: "..."
      homepage: ...
      args_id: "$args2"
      identifier: biotools:bcftools
args:
  - args:
      description: ""
  - args2:
      description: ""
input:
  - - meta:
        ...
    - vcf:
        ...

[awgymer]

This will also require an update to the nf-core/modules meta-schema.json

[awgymer]

Is this output format in nf-core modules info appropriate?