Rinkeby migration and example cleanup

[dwightjl]

• Update code examples from Kovan to Rinkeby
• Remove OpenEthereum/Parity examples now that OpenEthereum is deprecated.
• Remove code samples that are no longer included in the docs

Depends on the following PR: smartcontractkit/smart-contract-examples#16

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Name	Status	Preview	Updated
documentation	✅ Ready (Inspect)	Visit Preview	Jun 29, 2022 at 3:28PM (UTC)

[dwightjl]

Squashed and rebased to main

[aelmanaa]

please update this function (still using kovan)

function getHistoricalPrice() {
    document.getElementById('get-price-field').value = "loading...";
    const web3 = new Web3("https://kovan.infura.io/v3/34ed41c4cf28406885f032930d670036");
		const aggregatorV3InterfaceABI = [{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"description","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint80","name":"_roundId","type":"uint80"}],"name":"getRoundData","outputs":[{"internalType":"uint80","name":"roundId","type":"uint80"},{"internalType":"int256","name":"answer","type":"int256"},{"internalType":"uint256","name":"startedAt","type":"uint256"},{"internalType":"uint256","name":"updatedAt","type":"uint256"},{"internalType":"uint80","name":"answeredInRound","type":"uint80"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"latestRoundData","outputs":[{"internalType":"uint80","name":"roundId","type":"uint80"},{"internalType":"int256","name":"answer","type":"int256"},{"internalType":"uint256","name":"startedAt","type":"uint256"},{"internalType":"uint256","name":"updatedAt","type":"uint256"},{"internalType":"uint80","name":"answeredInRound","type":"uint80"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"version","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}];
		const addr = "0x9326BFA02ADD2366b30bacB125260Af641031331";
		const priceFeed = new web3.eth.Contract(aggregatorV3InterfaceABI, addr);

    // Valid roundId must be known. They are NOT incremental.
    let validId = BigInt("18446744073709562301");
    priceFeed.methods.getRoundData(validId).call()
      .then((historicalRoundData) => {
        document.getElementById('get-price-field').value = historicalRoundData.answer;
     	})
  }

[dwightjl]

I'm leaving those endpoint URLs alone for now. I need to get another endpoint started that we can use in the docs.