Add screen-mode command line argument

[alewis001]

Introduce a new "screen-mode" command line argument (-sm normal|half|full / --screen-mode normal|half|full) that allows a user to specify which screen mode (normal, half or full) Lazygit should use when it runs.

This argument will take precedence over a default Window Size specified in user config.

• PR Description

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[jesseduffield]

Could I ask what the rationale is behind this? If it's because right now we default to showing e.g. lazygit --filter <path> in full-screen rather than half-screen mode, we should just fix that default behaviour.

[jesseduffield]

Actually, funnily enough we need to make use of this for demos anyway: it was the lack of this arg that forced us to set the default to fullscreen in the first place. Not true, you can actually set it in the config.

[jesseduffield]

It's a shame we have the config being called WindowSize but elsewhere we call it screen mode. The reality is that screen-mode is better so I'm happy to use that here. I also doubt anybody is even using the config option.

[jesseduffield]

Nice work @alewis001

[alewis001]

Oh wow, great, thank you @jesseduffield. I was expecting to have to do more on it, I didn't know what but thought I'd need to do something :) Thank you for merging.