Feature Request: Support single-time pushes and retrievals.

[LJNeon]

File watching has always seemed less than ideal to me; as there are times when I want to retrieve files, times when I want to push files, and times when I don't want to do either. I find one-use commands like what the bitburner-sync package has far nicer and am currently using it for those.

To give recent examples:

• I can retrieve files from save A and the push them to save B.
• I can make updates to "hot" scripts that get executed by other scripts like my weaken/grow/hack scripts without worrying about my executor scripts failing unexpectedly due to them having been run with older code.