Added a utility contract and a JS script for upkeep interactions.

[SyedAsadKazmi]

Changes

• Added a solidity file named as UpkeepInteractions.sol, showcasing the interaction with AutomationRegistrar and KeeperRegistry contracts, for registration of Custom Logic Upkeep and performing other operations like pause upkeep, unpause upkeep, cancel upkeep, add funds to upkeep, withdraw funds from upkeep, and edit gas limit of upkeep.

• Added a script (upkeepInteractions.js) containing the functions to interact with the registered Custom Logic Upkeep.

Motive

Initially, I've created that as a utility contract and shared as a gist with the devs on Chainlink Discord, that are facing problems while registering and interacting with upkeep via contract.

Here are some of screenshots for the same:

So, on Bharath's suggestion, I've decided to create this PR. The contract code could possibly be added into the Register Upkeeps Programmatically section of the documentation, as it's a kind of extension of the same contract.

Kindly please review the PR, and let me know if any changes or add-ons are required from my end.

Thanks.

[andrejrakic]

This is great stuff, thanks for your contribution! I have couple of comments:

• Let's make json rpc url not hardcoded to Polygon Amoy Alchemy, rather just use JSON_RPC_URL env variable. That way developers can choose their own provider and blockchain network
• Let's make PRIVATE_KEY an env variable as well (process.env.PRIVATE_KEY), instead of having it as a string
• Let's avoid hardcoding addresses of KeeperRegistry and LinkToken contracts for Polygon Amoy, and instead allow developers to pass those programmatically
• Let's avoid mixing JavaScript promises and async/await syntax if possible, for example:

async function pauseUpkeep(upkeepId) {
    const tx = await keeperRegistry.pauseUpkeep(upkeepId);
    const receipt = await tx.wait();
    console.log(`Upkeep is paused successfully. Tx hash: ${receipt.hash}`);
}

[SyedAsadKazmi]

Thanks for the appreciation, @andrejrakic!

I've done the changes in the new commit, as you've mentioned. Kindly please review and let me know if any further changes are required from my end.

Thanks.