In-memory engine: load range check should be more flexible

[SpadeA-Tang]

Development Task

Now, when we load a range, if the range is overlapped with any type of ranges in the range_manager, the load will be rejected.
For example, if we want to mannually load a table whose range is "k1" - "k10", and now the "k6" - "k10" is already cached. The load will be rejected.
We may still want to load "k1" - "k6" in thsi case.