fix(logging): handle media server connection refused error/toast (#748)

* fix(logging): handle media server connection refused error/toast

Properly log as connection refused if the jellyfin/emby server is unreachable. Previously it used to
throw a credentials error which lead to a lot of confusion

* refactor(i8n): extract translation keys

* refactor(auth): error message for a more consistent format

* refactor(auth/errors): use custom error types and error codes instead of abusing error messages

* refactor(i8n): replace connection refused translation key with invalidurl

* fix(error): combine auth and api error class into a single one called network error

* fix(error): use the new network error and network error codes in auth/api

* refactor(error): rename NetworkError to ApiError

server/constants/error.ts

@@ -0,0 +1,5 @@
+export enum ApiErrorCode {
+  InvalidUrl = 'INVALID_URL',
+  InvalidCredentials = 'INVALID_CREDENTIALS',
+  NotAdmin = 'NOT_ADMIN',
+}