Always await expression of promise type in return position

[uniqueiniquity]

Fixes #27544

Currently, if a promise handler that is itself returning a promise is changed to an async function using our code fix, that promise is not awaited if it will be in a return position in the resulting async function. This was done since the following are equivalent in evaluation:

async function f() {
  return Promise.resolve(3);
}

async function g() {
  return await Promise.resolve(3);
}

However, if a rejected promise is returned from within a try block, awaiting the promise will cause it to be caught by the catch block, whereas returning it without an await will pass the rejected promise to the caller.

This PR changes the code fix behavior so promises returned by promise handlers will always be awaited, regardless of whether they are in a return position or not. This does mean that "unnecessary" awaits will be added, but for promises that might potentially be rejected but are, at the time of the code fix, not caught, the extra await may avoid later issues if wrapped in a catch after the fact.

Thanks @bterlson for input!

[amcasey]