Refactors the Relay to TIR python hook for the NPU so that optimizations
can be applied across the whole module and not just functions that will
be offloaded to the NPU. A pass `OutlineCompilerFunctions` is introduced
to outline NPU functions, which now happens before optimization passes
are run (this previously happened after the prim_func had been created).

In addition, optimization passes that should only run on NPU functions
are now limited to running on outlined functions for the NPU (by
checking the "Compiler" attribute). To help avoid code duplication, a
helpful decorator `create_npu_function_pass` has been created for python
passes that should only run on NPU functions.

This refactor helps move a number of passes in the microNPU codegen to
use an IRModule -> IRModule philosophy.

Change-Id: Icdea9ba43da0157d5ee17529d2b23b761396d112

Change-Id: I3ca48738e096bb0f4dc362f0e9550317fc0d5afd

This commit renames `npu_pass` -> `create_npu_function_pass`.

It also renames the `RelayToTIR` pass created in Python to `LowerToTIR`,
along with moving it to compiler.py to make it clear that this pass is a
wrapper around the `_lower_to_tir` function. In addition, to make it
explicit that the `lower_to_tir` func->func pass should not be used
directly it has been renamed to `_lower_to_tir` - it is being maintained
since it is used in many tests.

Change-Id: I3a0a06801f029aeaa4a51c2d86d8703bb0d7afbb

Change-Id: I44c64de15fa8680cc89ce0440ffa6c9e0ec62a50