preliminary shmptr

[libertyeagle]

Why are these changes needed?

Build shmptr prototype and implement libkoala's Box type with shmptr (instead of unique used in std's shmptr).

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Checks

• [ ] I've run scripts/format.sh to lint the changes in this PR.
• [ ] I've run scripts/clippy.sh to lint the changes in this PR.
• [ ] I've included any doc changes.
• [ ] I've made sure the tests are passing.
• Testing Strategy
  • [ ] Unit tests
  • [ ] Release tests
  • [ ] This PR is not tested :(