`dolt diff --summary` with cell-wise statistics

[andy-wm-arthur]

calculate edits in a cell-wise method, rather than the current row-wise method

[abmyii]

Both please, ideally!

[CaptainStabs]

An extra flag for --summary might be a good idea, cell-wise would be slower, and I only sometimes want a cell count

[timsehn]

This means changing this, a single column table with one row added:

test_drop_constraint $ dolt diff --summary
diff --dolt a/t b/t
--- a/t @ dhvdp8ur16g6mrkqia1m5nofb3oqnldd
+++ b/t @ 4ovq7l6evjbl5t0mfct7165t3ac90ece
prev size: 0, new size: 1, adds: 0, deletes: 0, modifications: 0
0 Rows Unmodified (0.00%)
1 Row Added (+Inf%)
0 Rows Deleted (0.00%)
0 Rows Modified (0.00%)
0 Cells Modified (NaN%)
(0 Entries vs 1 Entry)

to this:

test_drop_constraint $ dolt diff --summary
diff --dolt a/t b/t
--- a/t @ dhvdp8ur16g6mrkqia1m5nofb3oqnldd
+++ b/t @ 4ovq7l6evjbl5t0mfct7165t3ac90ece
prev size: 0, new size: 1, adds: 0, deletes: 0, modifications: 0
0 Rows Unmodified (0.00%)
1 Row Added (+Inf%)
0 Rows Deleted (0.00%)
0 Rows Modified (0.00%)
1 Cell Added (+Inf%)
0 Cells Deleted (0.00%)
0 Cells Modified (NaN%)
(0 Entries vs 1 Entry)

[timsehn]

@jennifersp is going to add this as she works on this one:

https://github.com/dolthub/dolt/issues/4043