Add a --size parameter to zellij run

[topisani]

This has been an important thing missing for me in automating zellij with kakoune.

Currently, the --size parameter allows either a percentage or an initial row/column count. Importantly, this row/column count does not result in a fixed-size pane, but is just an initial size, that is translated to percentage constraint. This is more useful in my case, but maybe that should be added as a separate SplitSize type instead.

Architecture-wise, this required passing the flag down through a lot of layers, and im unsure if there are better ways to do it.

Additionally, --direction left and --direction up have been fixed, which should close #3332

[topisani]

@imsnif In the context of your comment, i assume the same applies here. The second commit (direction bug fix) still seems relevant though to me though, right?

[imsnif]

Unless I misunderstood you, I don't think the same applies here as this doesn't seem client-specific.

I will however respectfully direct you at: https://github.com/zellij-org/zellij/blob/main/CONTRIBUTING.md#status-of-code-contributions-prs

I once again thank you for your work and willingness to contribute, but this project is large, extremely busy and my capacity is limited. I have to be mindful of my time and attention. I usually prefer solving such issues with larger more sweeping changes.

Thanks again for your understanding.

[topisani]

this project is large, extremely busy and my capacity is limited. I have to be mindful of my time and attention. I usually prefer solving such issues with larger more sweeping changes.

Fully understand and appreciate that. Feel free to leave this open or close it, however you prefer.