RDMR-1452 - Apply every element of a multi-element XML fragment

[usernuno]

Description

injectFragment applied only the first element of a fragment holding more than one, then exited with code 0 and reported the file as updated. An inject entry listing two permissions wrote one, and the build passed, so the app shipped without the second permission.

Cause

The @xmldom/xmldom bump from 0.7.5 to 0.8.15. Version 0.8.4 stopped inserting DOM nodes that are not well-formed (CVE-2022-39353). A document has exactly one root element, so xmldom converts content past the first root into text and escapes its < and > characters. Version 0.9 throws instead of converting. That reading of the spec is correct and this PR keeps it. The defect is that trampoline handed a fragment to a document parser, which 0.7 tolerated.

The previous commit described the mechanism correctly and drew the wrong conclusion from it. It filtered out the text following the first element as "the raw source a second root degraded to". The text is that, and it is also the caller's remaining elements, so the filter removed the evidence of the loss rather than the loss itself.

Fix

parseXmlFragment wraps the fragment in one temporary root before parsing. Every top-level node then arrives inside a well-formed document, and the parser never inserts anything that is not well-formed. A DOM fragment parser does the same thing with a context element, and xmldom exposes no such API. The wrapped form also parses on 0.9.12, where the bare fragment throws HierarchyRequestError, so the fix does not depend on 0.8 being lenient.

parseXmlFragment strips a leading declaration before wrapping. A fragment pasted in from a whole file would otherwise carry its <?xml ?> inside the wrapper, where it is neither well-formed nor printable, and the run failed in the formatter at commit time rather than where the fragment was written.

_mergeJson no longer assumes both trees have children. An element written with no children has no elements array at all, so merging into a self-closing <application /> threw target.elements is not iterable. That bug predates the bump, and this PR fixes it because it needs the same guard.

Checked against the previous build:

• A multi-element inject applies every element in document order.
• Comments and CDATA survive in place.
• A fragment carrying a declaration commits.
• Merging into a childless element works.
• Merge still de-duplicates by name and attributes.
• No change to setAttrs, deleteNodes, deleteAttributes or replaceFragment.

References https://outsystemsrd.atlassian.net/browse/RDMR-1452

Change Type

• Fix
• Feature
• Refactor
• Breaking Change
• Documentation
• Other (CI, chores, etc.)