Instantly update live search

[joliss]

Description of the Change

This change causes find-and-replace to react instantly to keystrokes in the findEditor (the "Find in current buffer" field), rather than after a 300ms debounce delay.

This is especially important when the scrollToResultOnLiveSearch setting is enabled, as it lets you instantly see when you're at the right place in the file, just like when you search a web page in Chrome.

Alternate Designs

One could make this behavior changeable with a setting. But I'm not sure if that's even necessary.

Benefits

Search feels snappier.

Possible Drawbacks

I haven't tested the performance impact of this with large buffers or on slower CPUs. We wouldn't want the editor to become unresponsive as you type into the search field.

Applicable Issues

When I tried running the test suite I had some failing tests on master, so I'm not sure if this broke any tests.

[Aerijo]

Instant update feels good, but it makes typing noticably slower with many matches (e.g., 20 000). I think work needs to be put into handling the many matches case first, before this can be merged.

Alternatively:

• There could be a mechanism to switch between delay and no delay, based on number of matches

• A custom delay time could be used, so it's faster than onDidStopChanging, which is used for more than just find and replace, but slow enough to let the user type.

[maxbrunsfeld]

I think that what we ultimately need to do is a two-step process:

• In an onDidChange callback, search the visible area. If there are no visible results after the cursor, find the next visible result for the purpose of supporting scrollToResultOnLiveSearch.
• Then, in an onDidStopChanging callback, search the entire buffer, in order to compute the result count and the Result n of m message.