fix: check for utils.disabled when changing signcolumn when leaving window

[evertonse]

Check if focus is disabled when changing signcolumn when leaving (WinLeave).

This solves the signcolumn getting changed upon lost focus of NvimTree window in floating mode despite being sure that NvimTree is in the ignore_filetypes.

    local ignore_filetypes = { 'neo-tree', 'NvimTree' }
    vim.api.nvim_create_autocmd('FileType', {
      group = augroup,
      callback = function(_)
        local is_floating = vim.api.nvim_win_get_config(0).relative ~= ''
        if vim.tbl_contains(ignore_filetypes, vim.bo.filetype) or is_floating then
          vim.b.focus_disable = true
          print('recognized focus filetype = ' .. vim.bo.filetype)
        else
          vim.b.focus_disable = false
        end
      end,
      desc = 'Disable focus autoresize for FileType',
    })

Before

Signcolumn disappear after losing focus

After

Corectly keeps the signcolumn padding when cursor leaves NvimTree window

[cryptomilk]

Thank you very much for your contribution. Could you please add a test for it?