ci: publish junit results for rust and acceptance tests

[stevennevins]

This PR publishes JUnit artifacts for op-acceptance-tests in CircleCI and updates the shared Rust CI test job to emit nextest JUnit XML.
It adds a repo-level rust/.config/nextest.toml ci profile so nextest writes target/nextest/ci/results.xml, then uploads that directory via both store_artifacts and store_test_results.
Validation in this workspace was limited to YAML and TOML parse checks.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 11.7%. Comparing base (53d3861) to head (05af875).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #20020      +/-   ##
===========================================
- Coverage     74.5%    11.7%   -62.9%     
===========================================
  Files          193      676     +483     
  Lines        10734    70997   +60263     
===========================================
+ Hits          8002     8322     +320     
- Misses        2588    62531   +59943     
  Partials       144      144              

Flag	Coverage Δ
cannon-go-tests-64	66.3% <ø> (ø)
contracts-bedrock-tests	79.4% <ø> (ø)
unit	0.5% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.
see 483 files with indirect coverage changes

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