As a pointer API consumer
I want be able to provide a pointer name or a pointer address when getting or updating pointers
So that as an owner of a pointer I can more easily resolve the pointer, without knowing the address

Given pointer_service.rs has update_pointer and get_pointer functions
When address is not a mutable address (tested via is_mutable_address in resolver_service.rs)
Then assume it is a pointer name
And attempt to resolve the pointer name to the address using 'Client::register_key_from_name' (see example code below)

Given pointer_service.rs update_pointer and get_pointer functions currently accept an address
When names are also supported
Then addresses continue to be supported, without any regressions

Implementation Notes

- Place any unit tests at the bottom of the same file as the associated production code
- Increment patch version of anttp package in Cargo.toml
- Create a copy of this issue description and save to /spec using the name of this issue as the filename (with lower underscore case, starting with the 5 char padded issue number, e.g. 00001_issue_title.txt)
- Update pointer_service.rs unit tests

Example code:

```
let secret_key = self.get_data_key(data_key)?;
let pointer_key = Client::register_key_from_name(&secret_key, name.as_str());
let pointer_hex = pointer_key.public_key().to_hex();
let pointer_address = PointerAddress::from_hex(pointer_address);
```