WDL Expressions in workflow input definitions

[mr-c]

Example:

wdl-cwl-translator/wdl2cwl/tests/wdl_files/blast.wdl

Line 12 in 1fff15b

String Outfile = basename(queryfa)+'.blast_result.txt'

1. Synthesize a new step to compute a static value for each dynamic input, something like _calc_{inputname}: _calc_Outfile with a single output named result
2. Rewrite all references to the original dynamic input to this static value: basically connecting _calc_OutFile/result instead of Outfile in all of the WorkflowStep.in sections