feat: add Amvstrm as provider for stream URL

Summary:

Test Plan:

src/controllers/episodes/getEpisodeUrl/index.spec.ts

@@ -90,4 +90,45 @@ describe('requests the "/episodes/:id/url" route', () => {
     expect(response.json()).resolves.toEqual({ success: false });
     expect(response.status).toBe(404);
   });
+
+  it("with sources from Amvstrm", async () => {
+    const response = await app.request(
+      "/episodes/1/url",
+      {
+        method: "POST",
+        body: JSON.stringify({
+          provider: "amvstrm",
+          id: "ore-dake-level-up-na-ken-episode-2",
+        }),
+        headers: { "Content-Type": "application/json" },
+      },
+      {
+        ENABLE_ANIFY: "true",
+      },
+    );
+
+    expect(response.json()).resolves.toEqual({
+      success: true,
+      result: {
+        source:
+          "https://www032.vipanicdn.net/streamhls/aa804a2400535d84dd59454b28d329fb/ep.1.1712504065.m3u8",
+        subtitles: [],
+        audio: [],
+      },
+    });
+  });
+
+  it("with no URL from Amvstrm source", async () => {
+    const response = await app.request("/episodes/-1/url", {
+      method: "POST",
+      body: JSON.stringify({
+        provider: "amvstrm",
+        id: "unknown",
+      }),
+      headers: { "Content-Type": "application/json" },
+    });
+
+    expect(response.json()).resolves.toEqual({ success: false });
+    expect(response.status).toBe(404);
+  });
 });