Add pre-commit hook

First pass at adding a pre-commit hook to enforce
formatting and linting standards.

This adds the pre-commit command to run on a
limited set of directories. Subsequent changes
will remove excluded folders and run formatting on
them as well.

The command will use the standard pre-commit hooks
for yaml, whitespace, and end of line linting.

It will also use `ruff` configured identically to
the Python SDK repositories, except for disabling
unused import checks ("F401"), as there are known
imports that are unused in the module but imported
in other modules. This is common in `compat` but
in other places as well.

The intention is to start enforcing formatting and
linting standards on edited code. Running the
pre-commit hook manually will make numerous
changes that should be broken into multiple
phases.

.pre-commit-config.yaml

@@ -0,0 +1,29 @@
+exclude: "\
+    ^(\
+    .changes|\
+    .github|\
+    awscli/examples|\
+    awscli/topics|\
+    awscli/botocore|\
+    awscli/s3transfer|\
+    awscli/doc|\
+    exe/assets|\
+    tests/functional/cloudformation/deploy_templates/booleans/input.yml|\
+    tests/functional/cloudformation/deploy_templates/nested-tag/input.yml|\
+    tests/|\
+    CHANGELOG.rst|\
+    configure\
+    )"
+repos:
+  - repo: 'https://github.com/pre-commit/pre-commit-hooks'
+    rev: v4.5.0
+    hooks:
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.4.8
+    hooks:
+      - id: ruff
+        args: [ --fix ]
+      - id: ruff-format

CONTRIBUTING.rst

@@ -67,7 +67,7 @@ Also, ensure your commit messages match this format::
     Describe your changes in the imperative mood, e.g.
     "Add foo to bar", "Update foo component for bar",
     "Fix race condition for foo".
-    
+
     The body of the commit message can include:
 
     * an explanation of the problem and what this change
@@ -120,6 +120,28 @@ can run these commands::
 When you push to your remote, the output will contain a URL you
 can use to open a pull request.
 
+Codestyle
+---------
+This project uses `ruff <https://github.com/astral-sh/ruff>`__ to enforce
+codstyle requirements. We've codified this process using a tool called
+`pre-commit <https://pre-commit.com/>`__. pre-commit allows us to specify a
+config file with all tools required for code linting, and surfaces either a
+git commit hook, or single command, for enforcing these.
+
+To validate your pull request prior to publishing, you can use the following
+`installation guide <https://pre-commit.com/#install>`__ to setup pre-commit.
+
+If you don't want to use the git commit hook, you can run the below command
+to automatically perform the codestyle validation:
+
+.. code-block:: bash
+
+    $ pre-commit run
+
+This will automatically perform simple updates (such as white space clean up)
+and provide a list of any failing checks. After these are addressed,
+you can commit the changes prior to publishing the pull request.
+
 
 Reporting Issues
 ----------------

pyproject.toml

@@ -130,3 +130,70 @@ markers = [
 
 [tool.black]
 line-length = 80
+
+[tool.isort]
+profile = "black"
+line_length = 79
+honor_noqa = true
+src_paths = ["awscli", "tests"]
+
+[tool.ruff]
+exclude = [
+    ".bzr",
+    ".direnv",
+    ".eggs",
+    ".git",
+    ".git-rewrite",
+    ".hg",
+    ".ipynb_checkpoints",
+    ".mypy_cache",
+    ".nox",
+    ".pants.d",
+    ".pyenv",
+    ".pytest_cache",
+    ".pytype",
+    ".ruff_cache",
+    ".svn",
+    ".tox",
+    ".venv",
+    ".vscode",
+    "__pypackages__",
+    "_build",
+    "buck-out",
+    "build",
+    "dist",
+    "node_modules",
+    "site-packages",
+    "venv",
+]
+
+# Format same as Black.
+line-length = 79
+indent-width = 4
+
+target-version = "py38"
+
+[tool.ruff.lint]
+# Enable Pyflakes (`F`) and a subset of the pycodestyle (`E`)  codes by default.
+# Unlike Flake8, Ruff doesn't enable pycodestyle warnings (`W`) or
+# McCabe complexity (`C901`) by default.
+select = ["E4", "E7", "E9", "F", "UP"]
+ignore = ["F401"]
+
+# Allow fix for all enabled rules (when `--fix`) is provided.
+fixable = ["ALL"]
+unfixable = []
+
+# Allow unused variables when underscore-prefixed.
+dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+
+[tool.ruff.format]
+# Like Black, use double quotes for strings, spaces for indents
+# and trailing commas.
+quote-style = "preserve"
+indent-style = "space"
+skip-magic-trailing-comma = false
+line-ending = "auto"
+
+docstring-code-format = false
+docstring-code-line-length = "dynamic"