Allocator api for immutable Buffer

[waynexia]

Which issue does this PR close?

For discussing #6336

Rationale for this change

What changes are included in this PR?

Implementing the Allocator for immutable Buffer correspondingly

Are there any user-facing changes?

Extra context

Notice that this patch would fail in some cases as I haven't change

arrow-rs/arrow-buffer/src/buffer/immutable.rs

Lines 319 to 322 in e67f17e

	let layout = match self.data.deallocation() {
	Deallocation::Standard(l) => l,
	_ => return Err(self), // Custom allocation
	};

[waynexia]

Sorry for the inconvenience. This branch is on top of waynexia:allocator-api. New change since 2ad2e3e