Add support for placeholders in entity name translations (#104453)

* add placeholder support to entity name translation

* add negativ tests

* make property also available via description

* fix doc string in translation_placeholders()

* fix detection of placeholder

* validate placeholders for localized strings

* add test

* Cache translation_placeholders property

* Make translation_placeholders uncondotionally return dict

* Fall back to unsubstituted name in case of mismatch

* Only replace failing translations with English

* Update snapshots

* Blow up on non stable releases

* Fix test

* Update entity.py

---------

Co-authored-by: Erik <erik@montnemery.com>
Co-authored-by: Joost Lekkerkerker <joostlek@outlook.com>

tests/testing_config/custom_components/test/translations/de.json

@@ -0,0 +1,10 @@
+{
+  "entity": {
+    "switch": {
+      "other1": { "name": "Anderes 1" },
+      "other2": { "name": "Anderes 2 {placeholder}" },
+      "other3": { "name": "" },
+      "outlet": { "name": "Steckdose {something}" }
+    }
+  }
+}

tests/testing_config/custom_components/test/translations/en.json

@@ -0,0 +1,11 @@
+{
+  "entity": {
+    "switch": {
+      "other1": { "name": "Other 1" },
+      "other2": { "name": "Other 2" },
+      "other3": { "name": "Other 3" },
+      "other4": { "name": "Other 4" },
+      "outlet": { "name": "Outlet {placeholder}" }
+    }
+  }
+}

tests/testing_config/custom_components/test/translations/es.json

@@ -0,0 +1,11 @@
+{
+  "entity": {
+    "switch": {
+      "other1": { "name": "Otra 1" },
+      "other2": { "name": "Otra 2" },
+      "other3": { "name": "Otra 3" },
+      "other4": { "name": "Otra 4" },
+      "outlet": { "name": "Enchufe {placeholder}" }
+    }
+  }
+}