Various updates and fixes

• Allow 2 tasks run at the same time, so that one does audio transcoding while the other does transcribing.
• If the video's audio codec is "aac", "mp3" or "pcm", the program will skip the transcoding and do directly copy. It greatly accelerates the overall speed. FasterWhisper itself will transcode all audio to wav file itself anyway. No point in doing slow transcoding.
• Batch process cards looks better with wider size and more info.
• Add a language widget in the right-lower corner of the home page, so now changing the language is super-easy.
• Now if in the setting "need video" is disabled, the Batch Process tasks will default to be "Audio/Video transcribe".
• Other program bugs.