[sui-execution] Re-implement wrapper script in Python

Replace the bash script with an equivalent python script.  This is to
prepare for a couple of improvements:

- Automating the creation of the new modules in `sui-execution`, and
  the `executor` and `verifier` dispatch functions.
- Adding `rebase` and `merge` commands to simplify keeping up with
  other changes in the execution layer.

Test Plan:

```
sui$ black scripts/execution-layer
sui$ flake8 scripts/execution-layer
sui$ ./scripts/execution-layer --dry-run cut v1
sui$ ./scripts/execution-layer cut v1
```

scripts/execution-layer

@@ -0,0 +1,104 @@
+#!/usr/bin/env python3
+# Copyright (c) Mysten Labs, Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+from os import chdir, remove
+from shutil import which, rmtree
+import subprocess
+from sys import stderr, stdout
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        prog="execution-layer",
+    )
+
+    parser.add_argument(
+        "--dry-run",
+        action="store_true",
+        help="Print the operations, without running them",
+    )
+
+    subparsers = parser.add_subparsers(
+        description="Tools for managing cuts of the execution-layer",
+    )
+
+    cut = subparsers.add_parser(
+        "cut",
+        help=(
+            "Create a new copy of execution-related crates, and add them to "
+            "the workspace.  Assigning an execution layer version to the new "
+            "copy and implementing the Execution and Verifier traits in "
+            "crates/sui-execution must be done manually as a follow-up."
+        ),
+    )
+
+    cut.set_defaults(do=do_cut)
+    cut.add_argument("feature", help="The name of the new cut to make")
+
+    return parser.parse_args()
+
+
+def do_cut(args):
+    """Perform the actions of the 'cut' sub-command.
+    Accepts the parsed command-line arguments as a parameter."""
+    cmd = cut_command(args.feature)
+
+    if args.dry_run:
+        cmd.append("--dry-run")
+        print(run(cmd))
+    else:
+        print("Cutting new release", file=stderr)
+        result = subprocess.run(cmd, stdout=stdout, stderr=stderr)
+
+        if result.returncode != 0:
+            print("Cut failed", file=stderr)
+            exit(result.returncode)
+
+        clean_up_cut(args.feature)
+        run(["cargo", "hakari", "generate"])
+
+
+def run(command):
+    """Run command, and return its stdout as a UTF-8 string."""
+    return subprocess.run(command, stdout=subprocess.PIPE).stdout.decode("utf-8")
+
+
+def repo_root():
+    """Find the repository root, using git."""
+    return run(["git", "rev-parse", "--show-toplevel"]).strip()
+
+
+def cut_command(feature):
+    """Arguments for creating the cut for 'feature'."""
+    return [
+        *["cargo", "run", "--bin", "cut", "--"],
+        *["--feature", feature],
+        *["-d", f"sui-execution/latest:sui-execution/{feature}:-latest"],
+        *["-d", f"external-crates/move:external-crates/move-execution/{feature}"],
+        *["-p", "sui-adapter-latest"],
+        *["-p", "sui-move-natives-latest"],
+        *["-p", "sui-verifier-latest"],
+        *["-p", "move-bytecode-verifier"],
+        *["-p", "move-stdlib"],
+        *["-p", "move-vm-runtime"],
+    ]
+
+
+def clean_up_cut(feature):
+    """Remove some special-case files/directories from a given cut"""
+    move_exec = f"external-crates/move-execution/{feature}"
+    rmtree(move_exec + "/move-bytecode-verifier/transactional-tests")
+    remove(move_exec + "/move-stdlib/src/main.rs")
+    rmtree(move_exec + "/move-stdlib/tests")
+
+
+if __name__ == "__main__":
+    for bin in ["git", "cargo", "cargo-hakari"]:
+        if not which(bin):
+            print(f"Please install '{bin}'", file=stderr)
+
+    args = parse_args()
+    chdir(repo_root())
+    args.do(args)

sui-execution/README.md

@@ -155,11 +155,11 @@ To use this flow:
 ## Making a Cut
 
 Cuts are always made from `latest`, with the process part automated by
-a script: `./scripts/cut_execution_layer.sh`.  To copy the relevant
-crates for a new cut, call:
+a script: `./scripts/execution-layer`.  To copy the relevant crates for
+a new cut, call:
 
 ``` shell
-./scripts/cut_execution_layer.sh -f <FEATURE>
+./scripts/execution-layer cut <FEATURE>
 ```
 
 Where `<FEATURE>` is the new feature name.  For a versioned snapshot