changed right left arrow to file icon

[iamnithishraja]

Fixes #2888

Changes:
made src button a file icon for a seemless experience. Made it same as on mobile devices on the desktop.
I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123

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[raclim]

Thanks for taking the time to work on this!

Usually for feature enhancements or requests like this that change the UI, we usually want to take some time to deliberate on what the final design would look like. After reviewing the issue I think it needs some further discussion, especially since it'll change a pretty highly used part of the interface. I'm sorry that it wasn't labeled properly at the time, but I don't think we're ready to merge this in yet. I'm going to close this for now, but please feel free to check out our other issues, thank you!