Update on "Add preserve_ops to EdgeCompileConfig"

1. Add `preserve_ops` to `EdgeCompileConfig`
2. Remove preserved ops from the decomposition table in `to_edge`.
3. Add checks to the verifier ensuring that preserved ops do not have mutations or views.
4. Update 'core_aten_exception_list' to be 'preserved_ops' in `to_edge_transform_and_lower`.

Context/Usage
**core_aten_ops_exception_list**
- Contains operators that are missing a decomposition to core aten.
- Exclude these so that verification can still be run on the rest of the graph.
- Ideally, this list should be empty.

**preserve_ops**
- Contains operators that the user specifically does not want decomposed.
- Must be aten; custom ops are ignored by verifier.

Edge case:
- If an aten operator does not have a decomp, and the user specifically wants it to be preserved, put it in preserve_ops rather than core_aten_ops_exception_list.

Differential Revision: [D78298749](https://our.internmc.facebook.com/intern/diff/D78298749/)

[ghstack-poisoned]

Author: lucylq

exir/verification/verifier.py

@@ -5,6 +5,7 @@
 # LICENSE file in the root directory of this source tree.
 
 import itertools
+import logging
 import operator
 import types
 from contextlib import nullcontext
@@ -134,16 +135,21 @@ def check_valid_op(self, op):
                 ):
                     return
                 if op in self._preserve_ops:
+                    if op.namespace != "aten":
+                        raise RuntimeError(
+                            f"Only preserve aten ops. Received op {op} with namespace {op.namespace}."
+                        )
                     # Preserved ops should not include mutation or view,
                     # which may affect memory planning.
-                    if op._schema.is_mutable or op.is_view:
+                    if op.is_view:
                         raise RuntimeError(
                             f"Cannot preserve operator {op} because it is a view or mutation."
                         )
-                    if op.namespace != "aten":
-                        raise RuntimeError(
-                            f"Only preserve aten ops. Received op {op} with namespace {op.namespace}."
+                    if op.is_mutable:
+                        logging.warning(
+                            f"Preserving mutation ops like {op} is a no-op because run_decomposition functionalizes it and prevents it from showing up."
                         )
+
                     return
                 if torch.Tag.core not in op.tags and torch.Tag.view_copy not in op.tags:
                     # NOTE(qihan): whether view_copy operators are marked as canonical is still under