To split the crate into two, several changes were made:
1. Most `pub(crate)` are now `pub` to allow access from Aya;
2. Parts of BpfError are merged into, for example, RelocationError;
3. BTF part of Features is moved into the new crate;
4. `#![deny(missing_docs)]` is removed temporarily;
5. Some other code gets moved into the new crate, mainly:
- aya::{bpf_map_def, BtfMapDef, PinningType},
- aya::programs::{CgroupSock*AttachType},
The new crate is currenly allowing missing_docs. Member visibility
will be adjusted later to minimize exposure of implementation details.
Refs: #473
Shenghui Ye