Mark formatting attributes with a common property

[mlewand]

Is this a bug report or feature request?

🆕 Feature request

💻 Version of CKEditor

CKEditor v5 @ 12.0.0

📋 Steps to reproduce

With introduction of attribtue properties in #1659 we should mark all the formatting markup with isFormatting property.

That way the remove format feature (#908) will be able to tell which attributes should be removed.

Related pull requests:

• Marked alignment attribute with the AttributeProperties#isFormatting property ckeditor5-alignment#38
• Marked font size and font family attributes with the AttributeProperties#isFormatting property ckeditor5-font#27
• Marked basic style attributes with the AttributeProperties#isFormatting property ckeditor5-basic-styles#86