home-assistant: Add commands to control photoframe

The digital photo frame in the kitchen is powered by a server service,
which exposes a minimal HTTP API.  Using this API, we can e.g. advance
or backtrack the displayed photo.  Exposing `rest_command` services
for these operations allows us to add buttons to dashboards to control
the frame.

home-assistant/configuration.yaml

@@ -54,6 +54,7 @@ automation: !include automations.yaml
 script: !include scripts.yaml
 scene: !include scenes.yaml
 shell_command: !include /run/config/shell-command.yaml
+rest_command: !include /run/config/rest-command.yaml
 
 lovelace:
   mode: storage

home-assistant/kustomization.yaml

@@ -27,6 +27,7 @@ configMapGenerator:
   - groups.yaml
   - restart-diddy-mopidy.sh
   - shell-command.yaml
+  - rest-command.yaml
   options:
     disableNameSuffixHash: true
     labels:

home-assistant/rest-command.yaml

@@ -0,0 +1,7 @@
+photoframe_next:
+  url: https://photos.pyrocufflink.blue/next
+  method: post
+
+photoframe_prev:
+  url: https://photos.pyrocufflink.blue/prev
+  method: post