Harden XSLT step against XXE attacks

[mgaffigan]

Parses the untrusted XML securely to prevent XXE attacks. Retains trust of the XML Stylesheet since that is not attacker controlled.

Review notes:

• See Harden XSLT step against XXE attacks for actual fix
• Most of this is regression tests

[github-actions]

Test Results

124 files  + 1  124 suites  +1   2m 52s ⏱️ + 1m 3s
698 tests + 8  698 ✅ + 8  0 💤 ±0  0 ❌ ±0 
722 runs  +20  722 ✅ +20  0 💤 ±0  0 ❌ ±0 

Results for commit 883de45. ± Comparison against base commit 9359d9a.

♻️ This comment has been updated with latest results.

[gibson9583]

Requesting changes before merge.

The new parsing path breaks valid XSLT transformations when a channel uses Xerces. The batch endpoint added in this PR also has two issues: it can report success without accepting a batch, and it retains all processed message payloads.

Please address the three inline comments. The two batch API issues also apply to PR #452 because both PRs include the same API change.

non-blocking

[gibson9583]

good to merge, items raised are non-blocking

[tonygermano]

I had requested in #452 that the commit messages be expanded. That applies here, too, especially since this PR has the same or similar commit that prompted the request in the other PR.

[mgaffigan]

@tonygermano

I had requested in #452 that the commit messages be expanded. That applies here, too, especially since this PR has the same or similar commit that prompted the request in the other PR.

You're welcome to rewrite the commit messages - I said everything I would think to say in them (short of asking a clanker to bloviate). If someone wants to know "what" changed, they have the git diff. I'm focusing on the "why".

[tonygermano]

@tonygermano

I had requested in #452 that the commit messages be expanded. That applies here, too, especially since this PR has the same or similar commit that prompted the request in the other PR.

You're welcome to rewrite the commit messages - I said everything I would think to say in them (short of asking a clanker to bloviate). If someone wants to know "what" changed, they have the git diff. I'm focusing on the "why".

@mgaffigan No longer necessary on this PR. You removed the large duplicate commit that also appears in the other PR. The remaining changes are small enough to not need additional explanation.