fix load data when escaped and enclosed are the same

[jycor]

We weren't actually escaping any characters and just deleting all the escaped characters.

fixes: dolthub/dolt#9884

[fulghum]

Looks good!

[Webbmekanikern]

Thanks - I took a look at the code, won't this allocate like crazy? Correct me if I'm wrong, but importing e.g. 100 000 rows of 10 columns each would in this case add 2 000 000 small allocations.

Using a strings.Builder would at least cut the number in half, while a buffer pool would basically reduce it to at most 1 allocation. I'm not familiar with Dolt's codebase though and understand if the latter isn't feasible in the big picture.