function to insert updated electricity mix data into exiobase SUTs

[jakobsarthur]

this function creates an extra row and column into the supply and use tables. The new row in the Use table should be the "grid electricity" sum of all electricity inputs of every activity. the new column should be a new activity "electricity grid" which uses the updated electricity mix from the entso data.
In the Supply table it there should be a new activity producing grid electricity (this should produce the same amount as of grid electricity as the activity electricity grid uses.

The output should be numpy SUT arrays with updated electricity information