Some providers do well with a "longer" debounce period (like ib) since
searching them too frequently causes latency and stalls. By supporting
both a min and max debounce period on keyboard input we can only send
patterns to the slower engines when that period is triggered via
`trio.move_on_after()` and continue to relay to faster engines when the
measured period permits. Allow search routines to register their "min
period" such that they can choose to ignore patterns that arrive before
their heuristically known ideal wait.
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