Add validation actions (#693)

* Add validation action

* Clean-up yaml

Removed trailing spaces

* Clean-up yaml

Removed trailing spaces

* Clean-up yaml

Removed trailing spaces

* Clean-up yaml

Removed trailing spaces

* Clean-up yaml

Removed trailing spaces

* Update validate_yaml.yml

* Validate on push

Only for nspanel_esphome.yaml and nspanel_blueprint.yaml

* Extending warnings for +255-char lines

* Update validate_yaml.yml

* Clean-up yaml

* Update validate_yaml.yml

* Clean-up yaml

* Clean-up yaml

* Clean-up yaml

* Clean-up yaml

* Clean-up yaml

* Update and rename validate_yaml.yml to validate_blueprint.yml

* Create validate_esphome.yml

* Clean-up yaml

.yamllint/rules.yml

@@ -0,0 +1,7 @@
+extends: relaxed
+
+rules:
+  # 255 chars should be enough, but don't fail if a line is longer
+  line-length:
+    max: 255
+    level: warning