Allow selecting a time range in the markers chart

Selecting a time range by dragging is for now only possible in the upper part of the profiler UI, it would be great if the markers chart could be used to select a region as well, as it's easier to start the mouse drag on the right marker when the mouse is on the marker.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-280)