I have repeating data in contiguous cells in a column. I want to insert a
row into the spreadsheet, each time a value in a cell below is not the same
as the value in the cell immediately above. This will create groupings of
identical values and a line between the groups.

What I have now:

AAAA
AAAA
AAAA
BBBB
BBBB
CCCC
DDDD

What a want:

AAAA
AAAA
AAAA

BBBB
BBBB

CCCC

DDDD