This commit only moves code without significant changes (the only changes is:
- corrected imports
- add imports to the doc comments which have become inaccessible
)

The following commit will not allow to call `reader.decoder()` while
reference to ResolveResult is valid, so we'll need to save decoder
before the loop and update it when it could be changed

… to it

This commit only moves code and do not introduce any improvements

This commit only moves code

`Deserializer` implementation can buffer events and it will not be able
to buffer the `resolve` result because it is bound to the `NsReader`

Co-authored-by: Daniel Alley <dalley@redhat.com>

…ll non-namespace-aware mutation methods

Because `impl DerefMut<Target=Reader> for NsReader` is removed, all Reader's
methods that accept `&mut self` won't be available for the NsReader, including
configuration methods.

Because we need a way to configure our reader, we need to reimplement necessary
methods that accepts `&mut self`. In order to not duplicate the code and the doc
of this configure methods, they was put into the macro `configure_methods!` and
embed to both readers.

Co-authored-by: Daniel Alley <dalley@redhat.com>