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"
```

src/auth/RegisterPage.tsx

@@ -44,7 +44,7 @@ import { Config } from "../config/Config";
 
 export const RegisterPage: FC = () => {
   const { t } = useTranslation();
-  usePageTitle(t("Register"));
+  usePageTitle(("action.register"));
 
   const { loading, authenticated, passwordlessUser, client, setClient } =
     useClientLegacy();
@@ -170,8 +170,8 @@ export const RegisterPage: FC = () => {
                 <InputField
                   type="text"
                   name="userName"
-                  placeholder={t("Username")}
-                  label={t("Username")}
+                  placeholder={t("common.username")}
+                  label={t("common.username")}
                   autoCorrect="off"
                   autoCapitalize="none"
                   prefix="@"
@@ -188,8 +188,8 @@ export const RegisterPage: FC = () => {
                     setPassword(e.target.value)
                   }
                   value={password}
-                  placeholder={t("Password")}
-                  label={t("Password")}
+                  placeholder={t("common.password")}
+                  label={t("common.password")}
                   data-testid="register_password"
                 />
               </FieldRow>
@@ -237,7 +237,7 @@ export const RegisterPage: FC = () => {
                   disabled={registering}
                   data-testid="register_register"
                 >
-                  {registering ? t("Registering…") : t("Register")}
+                  {registering ? t("Registering…") : ("action.register")}
                 </Button>
               </FieldRow>
               <div id={recaptchaId} />