Implement a XML Review UI that allow user to perform actions on XML files

Review Request #9615 — Created Feb. 10, 2018 and discarded — Latest diff uploaded

Information

Review Board
master

Reviewers

XML files is handled as an uneditble attachments in the current
version.
I implemented a new class XMLReviewUI that
enhence Review board's ability to process XML file.

Features:
- Smart indentation for the file
- Diff for the file will be shown in render and source format

Known issues:
- Due to the parser library issue, the XML Render cannot render
the text of an element that are after a child element.
(e.g. <parent>
<child>
</child>
info
</parent> )
info cannot be render in the example above.

Added and ran unit test with:
- Properly formatted XML files (attributes/children).
- Handle Highly-nested XML files.

Tested the development environment with:
- File diff system.
- Properly formatted XML files (attributes/children).
- Handle Highly-nested XML files.