allow efficient diffing from the command line (integrated with idahunt)

[saidelike]

An example of use for this is in idahunt. See detailed example in https://github.com/nccgroup/idahunt#binary-diffing where it shows how IDA is called and what environment variables are set. We obtain https://github.com/nccgroup/idahunt/blob/main/img/TmRecoverResourceManagerExt.png

The code changes consists in:

• distinguishing the code generation (assembly and pseudo code) from showing it in IDA, so we can generate the code from the command line without showing it
• support more DIAPHORA_AUTO + other environment variables to call it from the command line

[joxeankoret]

Thank you very much for your patches! I have written a review for this PR. I hope it finds you well, my aim is not to annoy or bother you.

[saidelike]

I've made additional changes and commented on your comments. Thanks for the feedbacks.

[saidelike]

I've made the additional changes based on your feedbacks. If you are happy with them, feel free to merge.

[joxeankoret]

And changes integrated. Thank you!