Helper module for validating an attachment in a draft/message before submitting to the Nylas API.
@type t() :: %ExNylas.Attachment.Build{ content: String.t() | nil, content_id: String.t() | nil, content_type: String.t() | nil, filename: String.t() | nil, id: String.t() | nil, is_inline: boolean() | nil, size: non_neg_integer() | nil }