refactor(api): replace plex-api package with internal implementation (#2335)

Removes plex-api dependency and its type declarations. Then extends the ExternalApi class for
PlexAPI implementation to mimick the exact same old behaviour. This should resolve the security
vulnerabilities in transitive dependencies: form-data(critical), request (moderate, deprecated),
tough-cookie (moderate), xml2js (moderate). Plex-api itself is also no longer maintained.

server/types/plex-api.d.ts

@@ -1,33 +0,0 @@
-declare module 'plex-api' {
-  export default class PlexAPI {
-    constructor(intiialOptions: {
-      hostname: string;
-      port: number;
-      token?: string;
-      https?: boolean;
-      timeout?: number;
-      authenticator: {
-        authenticate: (
-          _plexApi: PlexAPI,
-          cb: (err?: string, token?: string) => void
-        ) => void;
-      };
-      options: {
-        identifier: string;
-        product: string;
-        deviceName: string;
-        platform: string;
-      };
-      requestOptions?: Record<string, string | number>;
-    });
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    query: <T extends Record<string, any>>(
-      endpoint:
-        | string
-        | {
-            uri: string;
-            extraHeaders?: Record<string, string | number>;
-          }
-    ) => Promise<T>;
-  }
-}