feat: add blocks raw extrinsics endpoint (#1334)

* add fetchBlockRaw to block service

* add unit test
update latest e2e tests

* feat: add endpoint that queries a block by hash and returns it along with the raw values of its extrinsic(s)

* build docs

* update inline doc

* update number to 0xstring

* update BlockRaw docs summary and description

* update schema pattern

* update docs