New: Add no-unreachable-loop rule (fixes #12381)

[mdjermanovic]

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

[X] New rule

fixes #12381

Examples of incorrect code for this rule:

/*eslint no-unreachable-loop: "error"*/

while (foo) {
    doSomething(foo);
    foo = foo.parent;
    break;
}

function verifyList(head) {
    let item = head;
    do {
        if (verify(item)) {
            return true;
        } else {
            return false;
        }
    } while (item)
}

function findSomething(arr) {
    for (var i = 0; i < arr.length; i++) {
        if (isSomething(arr[i])) {
            return arr[i];
        } else {
            throw new Error("Doesn't exist.");
        }
    }
}

for (key in obj) {
    if (key.startsWith("_")) {
        break;
    }
    firstKey = key;
    firstValue = obj[key];
    break;
}

for (foo of bar) {
    if (foo.id === id) {
        doSomething(foo);
    }
    break;
}

What changes did you make? (Give an overview)

new rule: no-unreachable-loop

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

[nzakas]

@mdjermanovic are you still working on this?

[mdjermanovic]

Yes, sorry I didn't have much time last week,

[aladdin-add]

LGTM, thanks! better to have one more reviewer on this~