Apply resizeRowsByTallestCell to multiple columns

[tgreenwatts]

Currently resizeRowsByTallestCell operates on a column basis, so if i have a table

col1	col2
text	text
{3 lines}	{2 lines}

I want to resize so the second row is taller to fit all the contents. Today users would need to guess if they resize based on col1 or col2. Let's allow them to resize based on both and get the maximum across the columns

@philcchen has generously suggested he contribute this