Add debounceRequest function

[Half-Shot]

Fixes #332

This basically allows callers to call a function on the intent multiple times and await the same outcome, which we often do for bridges.

[Half-Shot]

NB I might decide to split this out to a utility class.

[tadzik]

Looks good, but I'd expect it to ship with something else in the code already using it, so that it doesn't exist in a vacuum :)