ptx: fixes

[usamoi]

• folding lower case letters to upper case for sorting, instead of folding upper case letters to lower case for sorting
• correctly esacping break file like ()[]^
• fixing --format option
• rejecting three or more files if GNU extension is not enabled
• allowing -b, --ignore-file and --only-file to accept - as input file

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/misc/stdbuf is no longer failing!
Congrats! The gnu test tests/misc/tee is no longer failing!

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/misc/stdbuf is no longer failing!

[Copilot]

Pull Request Overview

This PR fixes several issues with the ptx utility related to sorting, regex escaping, and option handling. It updates the ignore_case conversion to correctly fold lowercase letters to uppercase for sorting, improves the REGEX escaping logic for break files, and refines input/output operand handling when GNU extensions are disabled.

• Change ignore_case conversion from lowercase to uppercase.
• Replace custom REGEX character handling with regex::escape.
• Revise option parsing for --format and file operands based on GNU extension settings.

Reviewed Changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated no comments.

File	Description
src/uu/ptx/src/ptx.rs	Updated flag handling for output format; streamlined regex escaping; fixed case conversion for sorting; improved operand validation
tests/by-util/test_ptx.rs	Added tests for rejecting extra operands, regex escaping, and format options

Files not reviewed (2)

• tests/fixtures/ptx/break_file_escape: Language not supported
• tests/fixtures/ptx/break_file_regex_escaping.expected: Language not supported

Comments suppressed due to low confidence (2)

src/uu/ptx/src/ptx.rs:344

• Changing the conversion to uppercase for ignore_case now correctly implements folding lower case letters for sorting. Please ensure that all sorting-related functionality and tests are updated to reflect this behavior.

word = word.to_uppercase();

src/uu/ptx/src/ptx.rs:253

• The reworked handling of the '--format' option now uses get_one for parsing and then checks for -O/-T flags. Please verify that the precedence of these options is as intended and consider adding an inline comment to clarify the evaluation order.

if let Some(format) = matches.get_one::<String>(options::FORMAT) {

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/misc/stdbuf is no longer failing!