make de stepper play nice w sra browser

right now de stepper takes a samplesheet, which is awesome. but if someone wants to pull data from sra they need to go hunt down urls for that data themselves. we need to figure out how to incorporate our other very awesome thing, the sra browser stepper step. feel like there are ui/ux implications here that might make my head hurt.. but also it means trying to pull read metadata from sra, and i guess let ppl attempt to classify those cols (assuming theyre even useful) even though users may have little context about what those cols mean.

just a related note, think this ties into the isa-tab conversation w jonathan too.

this feels a large topic, needing discussion, no clear action to take yet.. maybe a good contender for a trial run w using github discussions if wed like to pursue that?