gh-123614: Add save function to turtle.py

[yngvem]

Adds a save(filename: str, overwrite: bool = False)-function to turtle.py with the following input validation:

• FileNotFoundError that explicitly state that the directory is missing if someone tries to save to an non-existing directory
• ValueError if the file exists and overwrite=False
• ValueError if the file does not end with ps or eps

Co-authored-by: Marie Roald 3594989+MarieRoald@users.noreply.github.com

• Issue: A save function in the Turtle module #123614

[ghost]

All commit authors signed the Contributor License Agreement.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[nineteendo]

Could you add documentation? And I would raise FileExistsError if the file already exists and overwrite is false.

[MarieRoald]

We have updated the documentation now and changed the code to use the FileExistsError and make sure that the all pipeline checks pass

[hauntsaninja]

Thank you!