[WIP] Implement `ArrowArrayStream`, `ArrowSchema` and `ArrowArray`

[cocoa-xu]

This PR added support for parsing ArrowSchema and convert ArrowArray to Elixir values in NIF. Formats listed below are supported

format	description
l	int64_t
c	int8_t
s	int16_t
i	int32_t
L	uint64_t
C	uint8_t
S	uint16_t
I	uint32_t
f	float
g	double
u	string
+s	struct

[cocoa-xu]

Currently, we can test it with mix run test.exs, and it should print something like

%Adbc.ArrowSchema{
  format: "+s",
  name: "",
  metadata: nil,
  flags: 2,
  n_children: 3,
  children: [
    %Adbc.ArrowSchema{
      format: "l",
      name: "i64",
      metadata: nil,
      flags: 2,
      n_children: 0,
      children: [],
      reference: nil
    },
    %Adbc.ArrowSchema{
      format: "g",
      name: "f64",
      metadata: nil,
      flags: 2,
      n_children: 0,
      children: [],
      reference: nil
    },
    %Adbc.ArrowSchema{
      format: "u",
      name: "str",
      metadata: nil,
      flags: 2,
      n_children: 0,
      children: [],
      reference: nil
    }
  ],
  reference: #Reference<0.2938969449.2598502403.117250>
}