Support for Add, Modify and Delete

[kefahi]

Thank you for the important contribution. I am planning to use crystal-ldap instead of invoking the respective ldap command-line utilities. (ldapsearch/ldapadd/...etc).

But I was wondering if crystal-ldap supports Add/Modify/Delete, and if not how easy would it be to add support? I'm happy to help.

[stakach]

currently it does not, as our clients didn't have a need or desire for us to write their directories and hence why the shard doesn't have a v1.x release

I used the ruby gem as the primary reference for the shard so it probably wouldn't be too hard to add the methods by looking at what they do:
https://github.com/ruby-ldap/ruby-net-ldap/blob/1baa9bf24f2d2a0e1a4bca53f3bdba964f28f6a1/lib/net/ldap/connection.rb#L626

I also don't have an LDAP server handy and was using https://www.forumsys.com/tutorials/integration-how-to/ldap/online-ldap-test-server/ to test

If you have time to contribute those operations that would be awesome!