feat: add override function

[AlejandroSuero]

I explained all better in #69 with more examples.

This feature will introduce the ability to override highlight groups using the theme's palette or hard coding it as it's done in theme.highlights.

This feature also let's the users and the developers see the available colours in the palette and their corresponding values.

Note

This screenshot was taken from inside require("cyberdream").setup

Closes #69

[scottmckendry]

Amazing! Thank you @AlejandroSuero for raising such a detailed and well-thought-out PR.

I do have one question, just looking through the code: How does having a function for overrides here improve on pulling in the colors with a require? For example:

{
        "scottmckendry/cyberdream.nvim",
        lazy = false,
        priority = 1000,
        config = function()
            local colors = require("cyberdream.colors").default -- Import the default cyberdream colors
            require("cyberdream").setup({
                theme = {
                    highlights = {
                        Constant = { fg = colors.cyan },
                    },
                },
            })
            vim.cmd("colorscheme cyberdream")
        end,
    },

I've checked out your PR to confirm, and we can still benefit from your updates to types by doing it this way, which is excellent!

[scottmckendry]

Never mind, I've answered my own question. The function works flawlessly when toggling between dark and light modes which isn't currently possible with the example in my previous comment.

Great work!