feat(sdk): implement clone on IggyClient

[patrickariel]

This makes it so that a single client instance can be easily shared between multiple owners.

[hubcio]

Adding Clone to IggyClient does not provide benefits since the internal mutex / rwlock already handles sharing.

• IggyClient contains an IggySharedMut<Box<dyn Client>> which already uses Arc<RwLock<T>> internally
• The client() method already returns a cloned IggySharedMut, giving you the sharing capability without cloning the entire structure
• The codebase is designed to share the internal mutex-protected client rather than cloning the entire IggyClient structure

And most importantly: we discourage to use single client. Shared client has worse performance than multiple client. If you clone() client, the calls to network will be done on same IggyClient across all clones, and access to it is protected.

BUT: if you really insist on this functionality, we can merge it ;)

[patrickariel]

Ok, makes sense. Maybe in the future this library can offer a pooled implementation (with deadpool?), to make it more easy/efficient.