Add tags to web interface

Hi, thanks for the great tool.

My current workflow for some ad hoc testing is to run `flashlight measure` and then run some different tests manually, checking out different code for each test. It would be super nice to add some tags to each test so that they are visible when comparing the results. I guess the simplest workaround is to run `flashlight` from the cli with some tags in the filename of the report, but it would be nice if you could do something similar in the webinterface.

Edit: I now discovered that the filenames are not shown in the report. That would also be a QOL change so I can see what I'm comparing.

Second edit: Saw now that you can use `--resultsTitle`