A single field in a table or struct.
vtable_slot is the byte offset within the table's vtable (4, 6, 8, ...).
It's nil for struct fields, which use inline offsets in
Flatbuf.Schema.Struct.layout.
Summary
Types
@type t() :: %Flatbuf.Schema.Field{ attributes: map(), default: any(), docs: [String.t()], line: pos_integer() | nil, name: atom(), type: Flatbuf.Schema.type_spec(), vtable_slot: non_neg_integer() | nil }