[Feat] Symbol Picker Relative to Window

[farzad-memryx]

The issue I mentioned this in originally was closed, so mentioning here for easier tracking. The symbol picker is currently created relative to editor, and though the default config lists this is an option, changing relative to win produces errors.

    {
        'bassamsdata/namu.nvim',
        config = function()
            require('namu').setup({
                namu_symbols = { options = { window = { relative = 'win' } } },
            })
        end,
    },

Error executing vim.schedule lua callback: ...l/share/nvim/lazy/namu.nvim/lua/namu/selecta/selecta.lua:737: floating window cannot be relative to itself

[bassamsdata]

Thank you for opening this issue. I really forgot to work on it.