[feature request] Copy alert content from label

Hi,

We're currently using karma, and often find that we want to copy the content of a label. Right now we all handle the task differently -- some of us click the label then copy from the filter part; others click on a link to our log service and copy the value from there (others use pin-point accuracy and select the text and use ctrl-c). However, some way to easily copy from Karma itself would be nice.

For instance, a label with the content host: abc.xyz.001.fff could be made "copy-clickable" either with a small copy icon, or with a keyboard shortcut (ie, "if ctrl is held down, clicking on a label will copy the content of the label"; in my earlier example this would then be abc.xyz.001.fff (host: is not useful).

A small risk with a copy icon is that the grid would become more cluttered than it needs to be; I'm personally leaning more toward a "key + click = copy" solution -- if it's something you think could be useful, I can implement it and submit a PR.