feat: add get_all_worksheet_values to Spreadsheet

[Gardner-Programs]

Summary

Implements #1002. Closes the feature request for fetching all worksheet values in a single API call.

This is a rewrite of #1180 against the current codebase, addressing all feedback from that review.

Changes

• Added get_all_worksheet_values() to Spreadsheet with an optional skip_worksheet_titles parameter
• Added extract_title_from_range() helper to utils.py with SHEET_TITLE_RE regex
• Used absolute_range_name() to properly escape sheet titles before passing to values_batch_get
• Regex handles all valid sheet title formats: unquoted, quoted with spaces, and titles containing apostrophes (SQL-style '' escaping)
• Used None as default for skip_worksheet_titles to avoid mutable default argument issue raised in get_all_worksheet_values feature #1180 review

How it works

1. Calls self.worksheets() to get all sheet titles
2. Filters out any titles in skip_worksheet_titles
3. Wraps each title with absolute_range_name() to handle special characters
4. Fetches all data in one values_batch_get call
5. Parses the response into a {sheet_title: values} dict using extract_title_from_range()
6. Returns early with {} if all sheets are skipped (avoids an empty API call)

Tests

• test_extract_title_from_range in utils_test.py — covers unquoted, quoted, apostrophe, and invalid input cases
• test_get_all_worksheet_values in spreadsheet_test.py — covers normal retrieval and skip functionality via VCR cassette

[antoineeripret]

Hi @Gardner-Programs,

Thank you for the PR.

• Could you also update the documentation before I have a look at the PR? (in this file)
• Can you also explain how you generated the cassette file please?

Thank you !

[Gardner-Programs]

Thanks for the review!

Docs: I added a "Getting All Values From Every Worksheet at Once" section to docs/user-guide.rst, following the style of the surrounding "Getting All Values…" sections.

Cassette: originally I based the cassette on the ones already saved for testing, and I missed the live recording section in CONTRIBUTING.md. Sorry about that. I've generated a new one properly using OAuth, since a service account just errors out now (Google no longer gives service accounts any storage space, so it won't let them create files and client.create() fails with storageQuotaExceeded).

[antoineeripret]

Thanks @Gardner-Programs :)

I've reviewed it / tested it and LGTM. I'll approve the workflow to run now and if we don't have any issue, I'll merge it.