Heavily refactor and add more features to map syncer

- Add unit tests
- Add support for MQTT trigger
- Support gracefull shutdown triggered by sinals
- Introduce linting tools: isort, ruff, black
- Add support for monitoring with healthheck.io compatible
  endpoint
- Add basic README.md
- Make code compatible with Python 3.8 to support Ubuntu 20.04

tools/map_syncer/.envrc

@@ -0,0 +1,3 @@
+if [ -f .pyenv/bin/activate ]; then
+    source .pyenv/bin/activate
+fi

tools/map_syncer/.gitignore

@@ -0,0 +1,4 @@
+.pyenv/
+__pycache__/
+.mypy_cache/
+.pytest_cache/

tools/map_syncer/README.md

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+Map Syncer
+==========
+
+A daemon for keeping a directory with maps in sync with the maps-metadata repo.
+
+It supports:
+
+- Delayed deletion of maps that are no longer listed as live
+- Periodic time based sync
+- Sync on demand triggered by MQTT message
+- Monitoring via reporting to https://healthchecks.io/ compatible endpoint
+
+Production
+----------
+
+Copy `map_syncer.py` to target and run `./map_syncer.py --help` to see
+available options.
+
+The only runtime dependency on top of Python >= 3.8 is `paho-mqtt`. On Debian
+based systems it's `python3-paho-mqtt` package.
+
+Development
+-----------
+
+### Setup
+
+```sh
+python3 -m venv .pyenv
+source .pyenv/bin/activate
+pip install -r requirements.txt
+```
+
+### Lint
+
+```sh
+black .
+isort .
+ruff .
+mypy
+```
+
+### Test
+
+```sh
+pytest
+```