feat(mux): Support splitting Kitty multiplexer panes

[mochouaaaaa]

Fixes #205

How to test

Ensure you've run post-install hooks for kitty; I think you can do this via :Lazy sync<cr>

1. Use following config in a Kitty multiplexer session:

-- the actual keys `<M-C-k>` can be whatever you'd like
vim.keymap.set("n", "<M-C-k>", function()
    mux.split_pane("up")
end)
vim.keymap.set("n", "<M-C-j>", function()
    mux.split_pane("down")
end)
vim.keymap.set("n", "<M-C-h>", function()
    mux.split_pane("left")
end)
vim.keymap.set("n", "<M-C-l>", function()
    mux.split_pane("right")
end)

2. Use the keymaps, they should create kitty splits

[mrjones2014]

Looks like there is one Luacheck warning that needs to be resolved, but looks good other than that. https://github.com/mrjones2014/smart-splits.nvim/actions/runs/9360568332/job/25782345774?pr=206#step:6:15