prevent memory leak by making sure all memory allocated by `prepare_prelinked_interpretation` is freed once the constructed `PrelinkedInterpretationEnvironment` is not used anymore

What does this MR do?

This prevents memory leaks by making sure all memory allocated by prepare_prelinked_interpretation is freed once the constructed PrelinkedInterpretationEnvironment is not used anymore. When running unit tests, for each test, a new IWorld is constructed and prepare_prelinked_interpretation is used.

I do the following:

• After the PrelinkedInterpretationEnvironment is constructed, I free all memory allocated for the program, except the code, directly. As far as I can see, this is safe, but please verify this!
• I use a finalizer to free the memory for the code, at the point the PrelinkedInterpretationEnvironment is garbage collected.

Changes to public APIs

none

Author's checklist (required)

• If bugs have been solved, tests have been added (guidelines)
• A changelog entry has been added (guidelines)
• Newly added code is documented (guidelines)
• Newly added code has a style consistent with the rest of the repository
• Intermediate commits compile (use git rebase -i main if not)

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