Enable linting rules for non-awaited Promises inside of try / catch

[bmingles]

Returning promises from a try block without awaiting won't actually catch errors associated with the rejection of said Promise.

async function throwsError() {
  throw "Some error that was thrown.";
}

async function main() {
  const appEl = document.getElementById("app");

  try {
    await throwsError();
  } catch (err) {
    // This works since the rejected Promise is awaited
    appEl.innerHTML = "Error A";
  }

  try {
    throwsError();
  } catch (err) {
    // This won't catch since the Promise is resolved after the try / catch has been run
    appEl.innerHTML = "Error B";
  }
}

main();

There is an eslint rule that can guard against this issue:
https://typescript-eslint.io/rules/return-await/

// Note: you must disable the base rule as it can report incorrect errors
'no-return-await': 'off',
'@typescript-eslint/return-await': 'error',

We should enable it, and fix any offending code. Running this on web-client-ui, I currently see 2 offending places:

packages/iris-grid/src/IrisGridTableModelTemplate.ts valuesTable

packages/utils/src/ClipboardUtils.ts copyToClipboard