Fix: Bullet featherstone error with double precision bullet

[silverducks143]

bullet-featherstone plugin pulls single precision versions of bullet symbols even if bullet is compiled with double precision. This patch introduces a bullet precision check and sets BT_USE_DOUBLE_PRECISION accordingly.

🦟 Bug fix

Fixes #877

Summary

• Expected behavior:
  gz-physics builds correctly with both single and double precision bullet.

• Actual behavior:
  bullet-featherstone plugin pulls single precision bullet symbols, even if bullet is compiled with double precision. This doesn't cause a build failure, but it was caught by verify-elf checker.

• Steps to reproduce
  Build gz-physics with double precision bullet.
  CMake options:
  -GNinja
  -Wno-dev
  -DBUILD_TESTING=ON

Fix consists of an additional check in main CMakeLists.txt, that sets BT_USE_DOUBLE_PRECISION if bullet is double precision.

Checklist

• Signed all commits for DCO
• Added a screen capture or video to the PR description that demonstrates the fix (as needed)
• Added tests
• 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.
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