Upgrade SWIG requirement to `v4.1.1`

[nickbianco]

Brief summary of changes

This change upgrades the required SWIG version to 4.1.1 for two main reasons:

1. Native support for std::unique_ptr conversion.
2. Support for C++ attributes (e.g., [[deprecated]]).

In addition to upgrading the required SWIG version, I've removed all custom implementations of unique_ptr in the bindings and replaced them with SWIG macros.

Testing I've completed

• Add test coverage for std::unique_ptr<PositionMotion> in the bindings.
• Ran the existing Matlab/Python tests.

Looking for feedback on...

CHANGELOG.md (choose one)

• no need to update because...internal.

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This change is 

[nickbianco]

Thanks @aymanhab!