Add missing fields to the light sync state (#7225)

* Initial draft

* Add an iterator that helps us get most items

* Revert changes to grandpa

* Change fields to just be the grandpa authority set and babe epoch changes

* Only use the fields we need from the shared authority set

* Switch to RPC call

* Revert "Only use the fields we need from the shared authority set"

This reverts commit 6ede87b0c5fe53f251d7cb45951006a7dc8f9b83.

* Add babe_finalized_block_weight from `ashley-improve-sync-state-WIP-loading`

* Fix rpc test

* Move sync state rpc stuff into sc-sync-state-rpc

* Remove as_json_value and remove unwraps from sc-sync-state-rpc

* Add clone_inner to SharedAuthoritySet