feat(doom): Add `icon_offset` to entry menu options.

[polirritmico]

This should allow the user to add an indentation offset in cases where a font icon causes the cursor position not to align correctly with the first character of the menu description. For example:

{
  -- ...
  config = {
    center = {
      {
        action = "Lazy",
        desc = " Lazy",
        icon = "󰒲 ",
        icon_offset = 1,
        key = "<leader>cl",
      },
      -- etc...
    },
  },
},

Fix #422. I don't know if this is the correct approach, but it's simple enough and works for me.

Before:

After:

Regards

[glepnir]

seems like cursor position is not correct most like a bug

[polirritmico]

Closed for #424