[Player] Fix src= preloading with shaka

[enjikaka]

Shaka cannot preload raw files and browser-based HLS on Safari. Ignore shaka error SRC_EQUALS_PRELOAD_NOT_SUPPORTED when that happens as the preload manager is saved and asserted on later. Remove the preloadManager check in skipToPreloadedMediaProduct so that non-preloadable content also play when skipped to.