deprecate pbbam/pbmerge (maybe new module: pbtk/pbmerge)

[famosab]

Is there an existing module for this?

• I have searched for the existing module

Is there an open PR for this?

• I have searched for existing PRs

Is there an open issue for this?

• I have searched for existing issues

Are you going to work on this?

• If I'm planning to work on this module, I added myself to the Assignees to facilitate tracking who is working on the module

Additional info

This relates to #4753:

It seems to me that pbbam was archived and the individual tools were transferred to pbtk. Tackle the proper update on a separate branch with a separate PR.

After this new module is created, pbbam/pbmerge needs to be removed.

[sguizard]

pbmerged was used in the first version of the isoseq pipeline. After a modification of the analysis strategy, pbmerge has been removed and not used by any pipeline.
I've kept maintained it along with the other Pacbio modules to keep available in the hypothesis where would like to use it.
Unless someone planned to use it in a new pipeline, I don't think it's necessary to keep a module for pbmerge.

[SPPearce]

Note that pbmerge should be deprecated following the guidelines in: https://nf-co.re/docs/contributing/modules#deprecating-a-module