* cbor: allow user to control nesting
- Make the default read/write entrypoints allow infinite nesting.
- Add {read,write}_nested() entrypoints that allow the crate user to
control the depth of nesting that's allowed.
- Along the way, convert the write[_nested] variants to return a
`Result<(), EncoderError>` rather than a bool. This exposes
more failure information (and forces the caller to take notice
of those tailures), and allows use of the ? operator.
* fixup: transmute error
Co-authored-by: kaczmarczyck <43844792+kaczmarczyck@users.noreply.github.com>
