feat(filesystem): Customisable column width

[MastarCheeze]

I've added a width field to the configs so that the width of the columns displayed in the file explorer can be customised. Text that are too long are also truncated with … to prevent the columns from being offset.

Edit: vim.fn.printf is used instead of string.format to prevent an error when the width is more than 99.

Demo:

require("neo-tree").setup({
  default_component_configs = {
    last_modified = {
      width = 10,
    },
    created = {
      enabled = true,
      width = 30,
    },
  },
})

This is the fix mentioned in #1614.

[pynappo]

so far LGTM, could you add it to the README in the longer example as well? (i figure that if required_width is already in the readme example, width might as well be there as well)

[MastarCheeze]

I've added the options into the readme, thanks for the suggestion!

[pynappo]

ty! pinging @cseickel.