Make it easier to click samples in timeline after applying filters

After I drop samples in certain functions, or filter the stack with something, it sometimes become hard to click samples on the timeline. This is probably because the exact position I'm clicking has been filtered out, and thus the click ends up going to nothing.

If there is nothing in the timeline around the cursor at that point, that's probably expected, but when the filtered sample is just one or two which happen to be under the cursor while samples around are still there, it could be very confusing and inconvenient.

It would probably be helpful that if a click ends up falling on a filtered out sample, it picks the nearest available sample around it, and check if that sample is drawn within a certain range on the timeline (e.g. one or two px), and use it if so.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-716)