where clause should allow for "blockNumber" property

The graph supports s `block` argument https://thegraph.com/docs/graphql-api#queries that we can use to get the state of the blockchain at a specific block.

this can be supported easily by adding a few lines for `options.block` in https://github.com/daostack/arc.js/blob/d80b0c36c3ced43d72b4f120af5b7c7494637d57/src/utils.ts#L109

We need this for common, where we are using the 2.0.0-experimental build

While we are doing this, it would also be a good idea to have a more restrictive type on createGraphQLQuery() that limits the kind of argument you can pass - we did not catch this at first in our code because we could add the block argument without any type error or runtime error (it just skips the argument silently)