Fix CSV Writer::new to accept delimiter and make WriterBuilder::build use it

[gsserge]

Discovered in #1324 (comment)

The delimiter can be correctly configured via WriterBuilder. WriterBuilder::build() constructs the Writer in-line and does not use Write::new().

Currently, Write::new() does not have the ability to configure the delimiter. The function should be changed to accept it as a parameter, and then WriterBuilder::build() should use Write::new() instead of duplicating the code. The delimiter field in struct Writer can be removed, because it can only be configured when creating Writer.

[HaoYang670]

Just a small nit. The title should be Fix CSV not Fix cvs.
Also, same mistake is in the title of #1327