fix(packaging): move templates/ into decnet/ package so they ship with pip install

The docker build contexts and syslog_bridge.py lived at repo root, which
meant setuptools (include = ["decnet*"]) never shipped them. Agents
installed via `pip install $RELEASE_DIR` got site-packages/decnet/** but no
templates/, so every deploy blew up in deployer._sync_logging_helper with
FileNotFoundError on templates/syslog_bridge.py.

Move templates/ -> decnet/templates/ and declare it as setuptools
package-data. Path resolutions in services/*.py and engine/deployer.py drop
one .parent since templates now lives beside the code. Test fixtures,
bandit exclude path, and coverage omit glob updated to match.

decnet/templates/cowrie/honeyfs/etc/motd

@@ -0,0 +1,26 @@
+
+ * Documentation:  https://help.ubuntu.com
+ * Management:     https://landscape.canonical.com
+ * Support:        https://ubuntu.com/advantage
+
+  System information as of Mon Jan 15 09:12:44 UTC 2024
+
+  System load:  0.08               Processes:             142
+  Usage of /:   34.2% of 49.10GB   Users logged in:       0
+  Memory usage: 22%                IPv4 address for eth0: 10.0.1.5
+  Swap usage:   0%
+
+ * Strictly confined Kubernetes makes edge and IoT secure. Learn how MicroK8s
+   just raised the bar for K8s security.
+
+     https://ubuntu.com/engage/secure-kubernetes-at-the-edge
+
+Expanded Security Maintenance for Applications is not enabled.
+
+0 updates can be applied immediately.
+
+Enable ESM Apps to receive additional future security updates.
+See https://ubuntu.com/esm or run: sudo pro status
+
+
+Last login: Sun Jan 14 23:45:01 2024 from 10.0.0.1