Update Xlsx.php (fix overwriting drawingX.xml)

[deadfire24]

Fix overwriting file xl/drawings/drawingX.xml if already exist by merging content

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

Why this change is needed?

To use media and drawings at the same time by protecting against overwriting xl/drawings/drawingX.xml

[oleibman]

Aside from the php-cs-fixer, phpcs, and phpstan errors, all of which you will have to fix, I do not understand your use case. What is the problem you are trying to solve? Have you opened an issue for it? And, although it is probably premature to start on this until the other items are addressed, you will need a formal test case to demonstrate that it works as intended. For now, I am converting this PR to a draft.

[oleibman]

No update in over 6 months. Closing.