[eth-json-rpc-middleware] Some Infura RPC methods should be cached but are not

The following RPC methods take block parameters and yet are not covered in `blockTagParamIndex` and so are not being cached the same as other RPC methods which take block parameters:

* `eth_getBlockTransactionCountByNumber`
* `eth_getTransactionByBlockNumberAndIndex`
* `eth_getUncleByBlockNumberAndIndex`
* `eth_getUncleCountByBlockNumber`

Search the eth-json-rpc-middleware package for blockTagParamIndex and compare its entries with the four RPC methods named in the issue. Inspect nearby tests, add coverage for the missing methods, and consider the issue done when those block-parameter methods are cached consistently and the relevant tests pass.

Written by the indexing model from the issue text.