ci: add .pre-commit-config.yaml and .flake8 config

.flake8

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+# flake8 is a Python linting tool run by pre-commit as declared by our
+# pre-commit-config.yaml file.
+#
+# This configuration is compatible with the autoformatter tool black, and
+# further relaxed to not bug us with too small details.
+#
+# flake8 configuration reference:
+# https://flake8.pycqa.org/en/latest/user/configuration.html
+#
+[flake8]
+max-line-length = 88
+extend-ignore = C, E, W
+
+# Adjustments to linting
+builtins = c

.pre-commit-config.yaml

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+# pre-commit is a tool to perform a predefined set of tasks manually and/or
+# automatically before git commits are made.
+#
+# Config reference: https://pre-commit.com/#pre-commit-configyaml---top-level
+#
+# Common tasks
+#
+# - Run on all files:   pre-commit run --all-files
+# - Register git hooks: pre-commit install --install-hooks
+#
+repos:
+  # Autoformat: Python code, syntax patterns are modernized
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v2.32.1
+    hooks:
+      - id: pyupgrade
+        args:
+          - --py37-plus
+
+  # Autoformat: Python code
+  - repo: https://github.com/psf/black
+    rev: 22.3.0
+    hooks:
+      - id: black
+        args:
+          # --target-version should be all supported versions
+          - --target-version=py37
+          - --target-version=py38
+          - --target-version=py39
+          - --target-version=py310
+
+  # Autoformat: Python code
+  - repo: https://github.com/pycqa/isort
+    rev: 5.10.1
+    hooks:
+      - id: isort
+        args:
+          - --profile=black
+
+  # Autoformat: js, html, markdown, yaml, json
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v2.6.2
+    hooks:
+      - id: prettier
+        exclude_types:
+          # These are excluded initially as pre-commit was added but can
+          # absolutely be enabled later. If so, we should consider having a
+          # separate run of pre-commit where we configure a line spacing of 4
+          # for these file formats.
+          - html
+          - javascript
+          - css
+
+  # Misc autoformatting and linting
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.2.0
+    hooks:
+      - id: end-of-file-fixer
+        exclude_types: [svg, css, json]
+      - id: check-case-conflict
+      - id: check-executables-have-shebangs
+      - id: requirements-txt-fixer
+        # These files have requirements.in files associated with them, and are
+        # generated by pip-compile.
+        #
+        exclude: >
+          images/minesweeper/requirements.txt|
+          images/federation-redirect/requirements.txt
+
+  # Lint: Python code
+  - repo: https://github.com/PyCQA/flake8
+    rev: "4.0.1"
+    hooks:
+      - id: flake8