repl: backgrounding command to move awaits to "background" after tick
Moves top-level awaited values into "background" after a tick, allowing the user to continue using the repl while waiting for something that might take a while or never happen.
closes #17168 (closed)
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
repl