add flag to maintain tmp directory

[mbussolotto]

lots of code uses:

 tmpDir, err := os.MkdirTemp("", "MYDIR-*")

to create a tmp directory where save files, used by further steps. The tmp directories are deleted using:

defer os.RemoveAll(tmpDir)

making impossible to debug it. We should add a flag to disable the defer command

[cbosdo]

We could add a --keepTemp flag and hide it? The issue is that this should be used in 21 places and only 4 of them have access to global flags ATM.