More ergonomic API in esp-alloc for create HeapRegions

[Dominaezzz]

This code to create heap regions could be made much nicer. Ideally user should be able to write this with only 5 lines of code and an unsafe block.

esp-hal/examples/src/bin/wifi_coex.rs

Lines 62 to 80 in 2ff28b1

	static mut HEAP: core::mem::MaybeUninit<[u8; 72 * 1024]> = core::mem::MaybeUninit::uninit();
	#[link_section = ".dram2_uninit"]
	static mut HEAP2: core::mem::MaybeUninit<[u8; 64 * 1024]> = core::mem::MaybeUninit::uninit();
	unsafe {
	esp_alloc::HEAP.add_region(esp_alloc::HeapRegion::new(
	HEAP.as_mut_ptr() as *mut u8,
	core::mem::size_of_val(&*core::ptr::addr_of!(HEAP)),
	esp_alloc::MemoryCapability::Internal.into(),
	));
	// COEX needs more RAM - add some more
	esp_alloc::HEAP.add_region(esp_alloc::HeapRegion::new(
	HEAP2.as_mut_ptr() as *mut u8,
	core::mem::size_of_val(&*core::ptr::addr_of!(HEAP2)),
	esp_alloc::MemoryCapability::Internal.into(),
	));
	}

I'm thinking something along the lines of esp_alloc::HeapRegion::from_internal(HEAP2).

[MabezDev]

I think think forwarding attributes to the underlying memory region that the macro defines is the most flexible way to solve this.