This reverts commit https://github.com/ruby/csv/commit/5c6523da0a61.

This introduces another pbolem. We should try again later.

https://github.com/ruby/csv/commit/43a1d6fff1

It will improve performance a bit. (But I haven't confirmed it yet...)

https://github.com/ruby/csv/commit/06a65b0302

Ruby: [Bug #18245] [ruby-core:105587]

Reported by Hassan Abdul Rehman.

https://github.com/ruby/csv/commit/5c6523da0a

GitHub: fix GH-228

Reported by Rafael Navaza. Thanks!!!

https://github.com/ruby/csv/commit/81f595b6a1

https://github.com/ruby/csv/commit/e32b666731

GitHub: fix GH-225

With Ruby 3.0.2 and csv 3.2.1, the file

```ruby
require "csv"
File.open("example.tsv", "w") { |f| f.puts("foo\t\tbar") }
CSV.read("example.tsv", col_sep: "\t", strip: true)
```

produces the error

```
lib/csv/parser.rb:935:in `parse_quotable_robust': TODO: Meaningful
message in line 1. (CSV::MalformedCSVError)
```

However, the CSV in this example is not malformed; instead, ambiguous
options were provided to the parser. It is not obvious (to me) whether
the string should be parsed as

- `["foo\t\tbar"]`,
- `["foo", "bar"]`,
- `["foo", "", "bar"]`, or
- `["foo", nil, "bar"]`.

This commit adds code that raises an exception when this situation is
encountered. Specifically, it checks if the column separator either ends
with or starts with the characters that would be stripped away.

This commit also adds unit tests and updates the documentation.

https://github.com/ruby/csv/commit/cc317dd42d

https://github.com/ruby/csv/commit/a802690e11