Allow locally hosted RPC and Block Explorer Urls with wallet_addEthereumChain

[MicaiahReid]

Explanation

Currently, adding a chain using the wallet_addEthereumChain RPC method requires that the supplied chain has an array of RPC urls, with at least one of them being an HTTPS url.

This is a problem because locally hosted resources are considered secure, and users may want to programmatically add their own local chains (e.g. Ganache) to MetaMask.

This change instead requires that at least one of the urls is either HTTPS or locally hosted (url.hostname === "localhost" || url.hostname === "127.0.0.1").

The same change is made for the block explorer urls.

Manual testing steps

To test, run MetaMask and run ganache --port 8544 --chain.chainId 1338. Send the wallet_addEthereumChain RPC method to MetaMask with the payload:

{
    chainId: "0x53A",
    chainName: 'Ganache Test',
    nativeCurrency: { symbol: 'ETH', decimals: 18 },
    rpcUrls: [ 'http://127.0.0.1:8544' ],
    blockExplorerUrls: [ 'http://localhost:3000' ]
  }

Verify that the chain is successfully added to MetaMask.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[MicaiahReid]

I have read the CLA Document and I hereby sign the CLA

[Amphaal]

Many thanks for this PR @MicaiahReid ! Eager to use this patch ASAP 👍

[AS-Pando]

Just wanted to mention that this feature would really help me out. Right now I'm running a small hardhat instance for testing. I don't seem to have a problem adding my chain from the extension network page (settings/networks/add-network). As MicaiahReid mentioned, I'd rather add it programmatically because I'd like to allow the user to direct my d.app to whatever local chain they have installed.

[MicaiahReid]

@danjm Is there anything else needed to merge this? Merging is still blocked for me, but it looks like I've had two approvals?

[adonesky1]

In general would ask for tests here, but doesn't seem we currently have any test suites for our RPC middleware methods...

LGTM

[BelfordZ]

fixes #14416