Feature: Copy current timestamp + keybind

[treiber]

Summary:

Quite simply, have a menu option and optional keybind to copy the current timestamp of any video playing. Could be useful for automation; my needs are video annotations where I often note down the current timestamp as a marker.

[low-batt]

It requires a bit of configuration, but you can accomplish this with the current version of IINA. See the discussion in issue #3370. Read through the comments. By the end you can press a key and the time will be in the paste buffer.