Enable hardhat forking RSK mainnet

[koirikivi]

Enable npx hardhat node --fork (and related test patterns) with RSK. Requires a bit of patching because of RSK.

The hardhat patch is automatically applied after running npm install

There's a command (npm run fork:rsk-mainnet) to start a local node forking from mainnet (npm run fork:rsk-testnet for the testnet).
Forking can be also used in tests. Please refer to Hardhat forking documentation https://hardhat.org/hardhat-network/guides/mainnet-forking#resetting-the-fork

IMPORTANT!! Consider before merging

• This PR includes test hardhat task check-fork-patch to verify if the forking patch works. It will fail if there's no network connection or if the mainnet sovryn rpc node is down, which causes tests to fail.
• The patch will probably not work after hardhat is updated (we should get a patch upstream to hardhat, but it requires more work)
• This PR doesn't have the package-lock.json or yarn.lock modifications, because I'm not sure if we're using npm or yarn and which version of node and npm we're using package-lock.json is added too.
• There are some issues with eth_getStorageAt returning 0x0 -- a fix in progress. Should be fixed.
• The patch has not been tested extensively, though everything seems to work!

Technical details

Calling a forked node (hardhat node --fork MY_RSK_NODE_RPC_URL) failed with:

eth_call
Invalid JSON-RPC response's result.  Errors: Invalid value null supplied
to: RpcBlockWithTransactions | null/transactions: RpcTransaction
Array/0: RpcTransaction/v: QUANTITY, Invalid value null supplied to:
RpcBlockWithTransactions | null/transactions: RpcTransaction Array/0:
RpcTransaction/r: QUANTITY, Invalid value null supplied to:
RpcBlockWithTransactions | null/transactions: RpcTransaction Array/0:
RpcTransaction/s: QUANTITY

We use patch-package to patch the local hardhat installation, since there's no upstream patch

This patch is based on:
https://gist.github.com/0x0scion/0422f9135bc37642ba36d55b59e8b424

More reading:
NomicFoundation/hardhat#2395
https://github.com/NomicFoundation/hardhat/pull/2313/files
NomicFoundation/hardhat#2106

[tjcloa]

lgtm
to work around possible issues with future hh updates, i suggest:

1. create a hh task from the forking.test.js and remove the test as it does not test the domain logic; this way we can avoid false-negatives due to the node issues etc. when running the tests
2. add the PR comment as disclaimer and containing the instruction on removing the patch as .md doc;
   2.1. do a hook - overload hh task with initial warning with the doc link which can be removed once the patch is included in hh

[koirikivi]

@tjcloa changes lgtm

[dzarezenko]

Could you provide some instructions on how to apply this? I was trying to fork Harmony mainnet and received this error:

 An unexpected error occurred:

InvalidResponseError: Invalid JSON-RPC response's result.

Errors: Invalid value undefined supplied to : RpcBlockWithTransactions | null/totalDifficulty: QUANTITY