Migrate action, common, a11y translation keys

```
move () {
  FROM=$1 TO=$2 find public/locales -type f -exec sh -c 'jq ".$TO = .\"$FROM\" | del(.\"$FROM\") | del(..|nulls) | select(length > 0)" {} | sponge {}' \;
}

move "Avatar" "common.avatar"
move "Camera" "common.camera"
move "Close" "action.close"
move "Copied!" "common.copied"
move "Copy" "action.copy"
move "Copy link" "action.copy_link"
move "Encrypted" "common.encrypted"
move "Go" "action.go"
move "Home" "common.home"
move "Invite" "action.invite"
move "Loading…" "common.loading"
move "Microphone" "common.microphone"
move "No" "action.no"
move "Not encrypted" "common.unencrypted"
move "Password" "common.password"
move "Profile" "common.profile"
move "Username" "common.username"
move "Video" "common.video"
move "Register" "action.register"
move "Remove" "action.remove"
move "Settings" "common.settings"
move "Sign in" "action.sign_in"
move "Sign out" "action.sign_out"
move "Submit" "action.submit"
move "User menu" "a11y.user_menu"
move "Audio" "common.audio"
move "Display name" "common.display_name"
```

i18next-parser.config.ts

@@ -25,6 +25,4 @@ export default {
   output: "public/locales/$LOCALE/$NAMESPACE.json",
   input: ["src/**/*.{ts,tsx}"],
   sort: true,
-  // The key becomes the English version of the string
-  defaultValue: (_l, _ns, key) => key,
 };