Incorporate i18n into UI elements (#1471)

* Update zh-tw string table (till 975343d2)
* Prepare localization table
* Implement i18n for Performers & Tags
* Add "add" action strings
* Use Lodash merge for deep merging language JSONs

The original implementation does not properly merge language files, causing unexpected localization string fallback behavior.

* Localize pagination strings
* Use Field name value as null id fallback

...otherwise FormattedMessage is gonna throw when the ID is null

* Use localized "Path" string for all instances
* Localize the "Interface" tab under settings
* Localize scene & performer cards
* Rename locale folder for better compatibility with i18n-ally
* Localize majority of the categories and features

ui/v2.5/src/components/Shared/Modal.tsx

@@ -2,6 +2,7 @@ import React from "react";
 import { Button, Modal, Spinner, ModalProps } from "react-bootstrap";
 import { Icon } from "src/components/Shared";
 import { IconName } from "@fortawesome/fontawesome-svg-core";
+import { FormattedMessage } from "react-intl";
 
 interface IButton {
   text?: string;
@@ -58,7 +59,13 @@ const ModalComponent: React.FC<IModal> = ({
             onClick={cancel.onClick}
             className="mr-2"
           >
-            {cancel.text ?? "Cancel"}
+            {cancel.text ?? (
+              <FormattedMessage
+                id="actions.cancel"
+                defaultMessage="Cancel"
+                description="Cancels the current action and dismisses the modal."
+              />
+            )}
           </Button>
         ) : (
           ""
@@ -72,7 +79,13 @@ const ModalComponent: React.FC<IModal> = ({
           {isRunning ? (
             <Spinner animation="border" role="status" size="sm" />
           ) : (
-            accept?.text ?? "Close"
+            accept?.text ?? (
+              <FormattedMessage
+                id="actions.close"
+                defaultMessage="Close"
+                description="Closes the current modal."
+              />
+            )
           )}
         </Button>
       </div>