Moves USMNdArrayType into numba_dpex/core.

[diptorupd]

• Have you provided a meaningful PR description?
  • Introduces a numba like module organization for types.
  • Renames USMNdArrayType to USMNdArray
  • Changes and improvements to USMNdArray
    • Now directly inherits from numba.core.types.Array
    • Stores a device filter string attribute
    • Properly handle non-C contiguous layouts in the type definition
  • Add type aliases and short names for numba scalar types directly into numba-dpex
  • Needed updates to imports.
• Have you added a test, reproducer or referred to an issue with a reproducer?
  Existing tests were updated.
• Have you tested your changes locally for CPU and GPU devices?
  Yes

Fixes #830