feat: support for autosharding

[chaitanyaprem]

There are changes/enhancements being made to c-bindings and go-waku as part of autosharding which affects the API's.

Corresponding changes need to be made to rust-bindings to update the API's as well as documentation.

Changes include following

1. Protocol API's would now optionally take pubSubTopic and if not specified derive pubSubTopic from contentTopics
2. Node initialization also takesn in contentTopics and optionally pubSubTopic to initiate a waku-node
3. feat: update lightpush API for autosharding go-waku#774 (comment)

Further changes to be analyzed by looking at specific PRs TBD