Implement Structured MemcachedError for Enhanced Error Handling (#33)

* add + replace #25

* soundness

* more test for add + replace

* build faiure fix?

* closes #26

* mr conflict clean up

* detla is now associated value

* precondition that both storage and arth mode are not set

* make sure of writeIntAsASCII

* closes #30

* soundness

* added unit test

* unit test refactor no string formatting

* MemcachedConnection clean up

* merge main update

Author: dkz2