Remove old modules after storage2 transition (#446)

* [core] remove old storage module

# Conflicts:
#	core/src/storage/alloc/bump_alloc.rs
#	core/src/storage/alloc/dyn_alloc.rs
#	core/src/storage/cell/sync_cell.rs
#	core/src/storage/chunk/sync_chunk/chunk.rs
#	core/src/storage/collections/binary_heap/duplex_sync_chunk.rs
#	core/src/storage/collections/binary_heap/impls.rs
#	core/src/storage/collections/bitvec/block.rs
#	core/src/storage/collections/bitvec/pack.rs
#	core/src/storage/collections/bitvec/vec.rs
#	core/src/storage/collections/btree_map/impls.rs
#	core/src/storage/collections/btree_map/node.rs
#	core/src/storage/collections/hash_map/impls.rs
#	core/src/storage/collections/stash/impls.rs
#	core/src/storage/collections/vec/impls.rs
#	core/src/storage/value.rs

* [abi] remove old layout module

# Conflicts:
#	abi/src/layout.rs
#	abi/src/lib.rs

* [abi] remove abi_derive sub crate

# Conflicts:
#	abi/derive/src/has_layout.rs
#	abi/derive/src/impl_wrapper.rs
#	abi/src/lib.rs

* [core/derive] remove Flush and AllocateUsing derives + tests

* [abi] remove unused function

* [abi] remove unused tests and simplify imports