feat: Improve read_csv SQL table reading function defaults (better handle dates)

[alexander-beedie]

Several modest improvements to SQL table-read function:

• Sets "try_parse_dates=True" by default for read_csv.
• Raises a SQLSyntax error if more than one argument is passed (all read funcs).
• Adds extra test coverage (null vs empty string, dates) for CSV reads from SQL.

Example

df = pl.sql(f"SELECT * FROM read_csv('some_file.csv')").collect()

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.33%. Comparing base (13d68ae) to head (2841c92).

Files	Patch %	Lines
crates/polars-sql/src/table_functions.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16866      +/-   ##
==========================================
- Coverage   81.36%   81.33%   -0.03%     
==========================================
  Files        1425     1425              
  Lines      187910   187913       +3     
  Branches     2705     2705              
==========================================
- Hits       152885   152846      -39     
- Misses      34529    34571      +42     
  Partials      496      496              

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