feat: add support for base64 encoding

[zimt28]

Closes #10

[emadalam]

@zimt28 How about introducing a new type base64 instead of adding it as an additional option. I suggest this because using it as an option will make the option useless for cases where type: :str is not used. Furthermore, we already use types like :host, :uri etc which is nothing more than string, and other types like :num, :int etc are ultimately parsed from string. The whole point of this parsing is to ultimately get values from environment variable string values that can be translated/validated into some stricter business types.

Also it would be much easier to simply implement the additional parser function for this base64 use case, no other change would be required in the core setup or functionality elsewhere.

What do you think?

lib/mahaul/parser.ex

  def parse(val, :base64) do
    case Base.decode64(val) do
     {:ok, decoded} -> {:ok, decoded}
      _ -> @error_tuple
    end
  end

lib/mahaul/constants.ex#L14

@type var_type :: :str | :num | :int | :bool | :port | :host | :uri | :base64

lib/mahaul/constants.ex#L42

@supported_types [:str, :enum, :num, :int, :bool, :port, :host, :uri, :base64]

[emadalam]

P.S:

• Thank you for the PR ❣️
• Use dev branch to merge changes so we can make a single release on hex ✌️