This reimplements the CSV parser used by the (still experimental) Import CSV
node.
Reliability is improved by:
* Properly handling quoted fields.
* Unit tests.
* Generalizing the parser to be able to handle customized delimiter, quote and
escape characters (those are not exposed in the node yet though).
* More accurate detection of column types by actually taking all values of a
column into account instead of only the first row.
Performance is improved by designing the parser in a way that supports
multi-threaded parsing. I'm measuring about 5x performance improvement which
mainly comes from multi-threading. Some files I wanted to use for benchmarking
didn't load in the version that's in `main` but do load fine with this new
version.
The implementation is now split up into two parts:
1. A general CSV parser in `blenlib` that manages splitting a buffer into
records and their fields.
2. Application specific parsing of fields into e.g. floats and integers which
remains in `io/csv/importer`.
This separation simplifies unit testing and makes the core code more reusable.
Pull Request: https://projects.blender.org/blender/blender/pulls/134715
