Add "minimum sentence time length" feature

A lot of times some sentences in subtitles are just too fast to read.
Faster Whisper XXL creates a lot of this issues.
You can use SubtitleEdit to fix it, but I find it exhausting to fix the subtitle files one by one.
So now in the settings there are 2 new entries. If you enable this feature, by the end of transcribe this program will go through the ASR_DATA and fix sentences that have too little time length. Default value is 1500ms, which is 1.5 seconds. You can set the value yourself.