ADD IBAN FIELD TO STRUCTS AND UPDATE PARSING LOGIC

- Added `iban` field to the `IbanEx.Iban` struct to hold the full IBAN value. - Updated the parsing logic to populate
the new field. - Adjusted BBAN rules and tests for France and Brazil to reflect updated structures. - Improved error
handling and format validation routines.

lib/iban_ex/country/mu.ex

@@ -22,6 +22,14 @@ defmodule IbanEx.Country.MU do
 
   use IbanEx.Country.Template
 
+  def rules() do
+    [
+      bank_code: %{regex: ~r/[A-Z0-9]{6}/i, range: 0..5},
+      branch_code: %{regex: ~r/[0-9]{2}/i, range: 6..7},
+      account_number: %{regex: ~r/[0-9A-Z]{18}/i, range: 8..25}
+    ]
+  end
+
   @impl IbanEx.Country.Template
   @spec to_string(Iban.t()) :: binary()
   @spec to_string(Iban.t(), binary()) :: binary()