Investigate and replace all `XyzFree()` TPL functions with memory pool usage.

[lmwnshn]

Feature Request

Summary

Investigate all XyzFree() TPL functions.

From a high-level conversation with @pmenon, the TPL constructs like IndexIterator, TableVectorIterator, StorageInterface etc. shouldn't really need corresponding @indexIteratorFree(), @tableVectorIteratorFree(), @storageInterfaceFree() etc functions. Instead, these structures should allocate from the pool so that explicit cleanup is invisible / unnecessary.

This would prevent issues like #1481.

Solution

In general, constructs should inject the MemoryPoolAllocator into all STL structures.