Use a more robust CSV parser to auto-populate the attribute editor

[robyngit]

The "Fill from file" button in the attribute editor was implemented using a simple routine that reads just the start of a file and tries to find the header names. (See issue #202). A few limitations of this method that @amoeba mentioned are that:

(1) my approach does not like the presence of a UTF BOM and
(2) my approach doesn't handle quoted column names with commas inside them. Both of these aren't common IME.

We should consider using a more robust CSV parser, such as PapaParse or SheetJS

[robyngit]

PapaParse introduced in #2519. It's very lightweight, well supported, and robust. It can even be multi-threaded!