Define `ObjectAccessDenied` type for `ACCESS_DENIED` code. Provide
method to write/read human-readable reason.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Add `TypeLock` value to `Type` enum. Implement `Lock` type compatible
with corresponding message. Implement `ObjectLocked` and
`IrregularObjectLock` errors in `apistatus` package.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>