Add functionality to draw a line (MET) at a given eta/phi

[EdwardMoyse]

This is a request from ATLAS - the reason is that often the missing energy used in analysis is not the same as the missing energy calculated during reconstruction, so it often does not look correct to analysts.

Since this is expected to be used for Missing energy (MET), one option would be to add it here:

However I think this might be technically difficult. So another option would be to consider it a type of guideline, and add it to the bottom menu? If so, we would need to input the direction, length, colour and draw style

cc @Somya-Bansal159