Focusing problems. Implement focus locking

[RamPawar7]

So I was having some fun with recording timelapses but the result had many focusing issues. I don't know if it is because of this app or my device because when video recording on the default camera app on my device the camera seems to never focus correctly.

Here are the result of the timelapses (videos are compressed due to github)

https://github.com/woheller69/TimeLapseCamera/assets/96973076/15379998-fc89-4ebb-9167-de21e4af1fbd

https://github.com/woheller69/TimeLapseCamera/assets/96973076/772ad31f-68d4-4139-8bb4-ab8b6dea51a7

Please add a focus locking feature to the view finder to fix this issue.