Support Drawing in cell Read & Write

[raziel057]

Support for read & write of Image in Cell - Related to #4014

I must admit it was really complex to understand the relations between all xml (richData) files that have to be created / updated. I lost a lot of time comparing the structure with files edited in Excel and specifically figuring out the metadata.xml file had to be largely changed as soon as images are added in cells.

This branch is based on #4664

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

Support for read and write of Image in Cell - Related to #4014

Why this change is needed?

When an image is inserted in a cell in an XLSX document, PhpSpreadsheet is currently not able to read it. This PR allow to collect those images in order to find them when calling $objWorksheet->getInCellDrawingCollection(). It's also possible to get the Drawing object from from the related Cell.

The code is covered by tests and have been tested in real application - As shown bellow:

When I import the file with image inserted in the Cell, I have it now in $objWorksheet->getInCellDrawingCollection():

[rapaelector]

those can be remove as it is by default as 0