Ability to save plots with the .> operator

[rolandwalker]

Description

Ability to save plots with the .> operator, just like parquet files for dataframes.

Example:

select length(table_name) as len from information_schema.tables .| df['len'].plot.hist() .> output.png;

Checklist

• I added this contribution to the changelog.md file.
• I added my name to the AUTHORS file (or it's already there).
• To lint and format the code, I ran

  uv run ruff check && uv run ruff format && uv run mypy --install-types .