nf-core modules create - new --conda_name cli flag

[ewels]

In #961 @Erkison added a really nice feature where the user is prompted for a new name to find a bioconda package that is different from the nf-core/modules tool name. This kicks in if nf-core modules create cannot find a tool on bioconda by that name.

I suggested that we should probably also make this available through the cli in addition to just a prompt, and of course the need for this has come around sooner than expected (as it always does), courtesy of @drpatelh

So - feature request is to add a new flag --conda_name into the command which is passed through the code and used to search bioconda if given, without using any interactive prompts.