New: Add no-promise-executor-return rule (fixes #12640)

[mdjermanovic]

What is the purpose of this pull request? (put an "X" next to item)

[X] New rule

fixes #12640

Examples of incorrect code for this rule:

/*no-promise-executor-return: "error"*/

new Promise((resolve, reject) => {
    if (someCondition) {
        return defaultResult;
    }
    getSomething((err, result) => {
        if (err) {
            reject(err);
        } else {
            resolve(result);
        }
    });
});

new Promise((resolve, reject) => getSomething((err, data) => {
    if (err) {
        reject(err);
    } else {
        resolve(data);
    }
}));

new Promise(() => {
    return 1;
});

What changes did you make? (Give an overview)

no-promise-executor-return rule.

Is there anything you'd like reviewers to focus on?

[nzakas]

Overall looks good. Just one question about the error message. Sorry we missed this.

@kaicataldo can you take a look when you get a chance?

[nzakas]

Is this accurate? I think they can return values but the values are never exposed anywhere. Maybe, "Return values from promise executor functions cannot be read."?

[mdjermanovic]

Agreed, this message might be seen as technically incorrect. It's changed now, thanks!

[kaicataldo]

LGTM!

[btmills]

LGTM, thanks @mdjermanovic! I particularly appreciate how thorough the tests are.