Feature request: Allow to go back to auto-detect encoding

[agulabon11]

Is your feature request related to a problem? Please describe.
By default, cyberchef does auto-detect of the encoding. But once you set a specific encoding in the out pane, you cannot go back to "auto-detect" mode. Or at least I haven't found a way using UI.

Steps to reproduce:

1. Generate some output
2. In the output pane select a specific encoding (eg: UTF-8)
3. Change the output so the content is on a different encoding.

The output will not auto-detect the encoding anymore.

Describe the solution you'd like
There should be an option called "auto-detect" in the encodings drop down, to allow to go back to that mode.

Describe alternatives you've considered
The workaround is to bake the recipe, stripe the "oenc" from the URL and load again.

Additional context
Probably the same happens to line detection mode.