A new gui config flag 'portraitMode':<string> is added to influence when
LazyGit stacks its UI components on top of one another.
The accepted values are 'auto', 'always', 'never'.
'auto': enter portrait mode when terminal becomes narrow enough
'always': always use portrait mode unconditional of the terminal
dimensions
'never': never use portraid mode
Signed-off-by: Louis DeLosSantos <louis.delos@gmail.com>