Add common empty-world coverage for entity management behaviors

[XINJIANGMO]

🎉 New feature

toward comment #299

Summary

Stage 1 for test migration :

• Extend the common empty-world test to cover entity removal behavior:
  • removing models by handle, index, and name
  • removing nested models
  • verifying removed proxies remain safe to inspect
  • covering the nested-model removal crash regression
• Add common construction coverage for entities that were previously only
  tested in DART:
  • revolute joint attachment
  • prismatic joint attachment
  • box and sphere shape attachment
  • basic frame-semantics checks after manual construction
• Add common coverage for mesh and heightmap construction paths:
  • mesh attachment and scaled mesh attachment
  • image heightmap attachment
  • DEM heightmap attachment
  • casting generic shapes back to heightmap shapes
• Update build files only as needed for this test migration:

Test it

Checklist

• Signed all commits for DCO
• Added a screen capture or video to the PR description that demonstrates the feature
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• Updated Bazel files (if adding new files). Created an issue otherwise.
• While waiting for a review on your PR, please help review another open pull request to support the maintainers
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Generated-by: gpt-5.4-codex.

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[XINJIANGMO]

Bazel support in gz-common currently does not stably expose the Dem.hh loader path
https://github.com/gazebosim/gz-common/blob/4d0894e47d4a03986c079c1bcf3081b25dac068b/geospatial/BUILD.bazel#L16

so I removed the releated case in original DART test case

[Copilot]

Pull request overview

This PR expands the existing construct_empty_world common test coverage to validate additional entity construction and removal behaviors across physics engine plugins, as part of the broader test migration effort.

Changes:

• Add common empty-world tests for manual construction of joints (revolute/prismatic) and primitive shapes (box/sphere), including basic frame-semantics checks.
• Add common tests for mesh attachment (including scaled meshes) and image heightmap attachment, including casting back to a heightmap shape.
• Add a regression guard test to prevent crashes when removing a parent model that owns nested models, and update build dependencies for the new heightmap/geospatial usage.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/common_test/construct_empty_world.cc	Adds new common tests for joints/shapes, mesh/heightmap construction, and a nested-model removal crash regression guard.
test/common_test/CMakeLists.txt	Links the common tests against the project’s heightmap component to support new heightmap usage.
test/BUILD.bazel	Adds Bazel deps for //:heightmap and @gz-common//geospatial:geospatial needed by the new test code.

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