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 Plex-api itself is also no longer maintained.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/api/externalapi.ts

@@ -13,6 +13,7 @@ const DEFAULT_ROLLING_BUFFER = 10000;
 export interface ExternalAPIOptions {
   nodeCache?: NodeCache;
   headers?: Record<string, unknown>;
+  timeout?: number;
   rateLimit?: {
     maxRPS: number;
     maxRequests: number;
@@ -32,6 +33,7 @@ class ExternalAPI {
     this.axios = axios.create({
       baseURL: baseUrl,
       params,
+      timeout: options.timeout,
       headers: {
         'Content-Type': 'application/json',
         Accept: 'application/json',