feat: Add new APIs added in version 2.1.13 (#20)

* Add new APIs added in version 2.1.13

* id let -> const

* Revert "id let -> const"

This reverts commit c308d54.

* change definition liff.id to const

Co-authored-by: V5n <iguru.shou.5410070@gmail.com>

Co-authored-by: V5n <iguru.shou.5410070@gmail.com>

index.d.ts

@@ -143,6 +143,13 @@ declare global {
          */
         function getVersion(): string
 
+        /**
+         * Gets the user's LINE version.
+         *
+         * If a user opens the LIFF app using an external browser, null is returned.
+         */
+        function getLineVersion(): string | null;
+
         /**
          * Gets the language settings of the environment in which the LIFF app is running.
          */
@@ -247,6 +254,13 @@ declare global {
          */
         const ready: Promise<void>;
 
+        /**
+         * The property that holds the LIFF app ID (String type) passed to liff.init().
+         *
+         * The value of liff.id is null until you run liff.init().
+         */
+        const id: string | null;
+
         const bluetooth: {
             /**
              * Check if the Bluetooth plugin can be used.