Add manifests (#22699)

* Add manifests

* Update auto name

* Update codeowners

* Add requirements from platforms

* Minor cleanup

* Incorporate changes from awarecan PR

homeassistant/components/shell_command/manifest.json

@@ -0,0 +1,10 @@
+{
+  "domain": "shell_command",
+  "name": "Shell command",
+  "documentation": "https://www.home-assistant.io/components/shell_command",
+  "requirements": [],
+  "dependencies": [],
+  "codeowners": [
+    "@home-assistant/core"
+  ]
+}