Show contributions of all activities/biosphere flows of production activity

[StpdFox]

A seperate issue created from https://github.com/LCA-ActivityBrowser/activity-browser/issues/301

As said in the other issue :

Would be nice if I could see the contributions of all activities/biosphere flows of my production activity (=contribution of all foreground processes in my activity, level 1). We have a piece of code doing that calculation in a notebook in case you are interested, but we couldn't speed it up yet (it takes hours at the moment to do that calculation if many activities&LCIA methods (e.g. 32:17) are involved, but Chris gave us some inputs on how to speed up).

To which got responded : This does sound nice to have, but as you noted, it would have to be a completely new piece of code (which gives the user a warning of dramatically increasing calculation time). If you have the time I would welcome your contribution (heh). The code used to perform contribution analysis starts here.