Make read trimming optional

[TBradley27]

There are some studies which demonstrate that trimming of RNA-Seq reads does not have a substantial impact on the accuracy of the quantification of gene expression. For example, the following preprint:

https://www.biorxiv.org/content/10.1101/833962v1.abstract

Removing trimming from the workflow would substantially reduce overall workflow runtime.

Therefore, it would be beneficial if trimming in FilTar could be made optional at this stage, but made the default option nonetheless (until more thoughtful consideration is given to this topic by myself).