feat: added js solution (and tests) for challenge palindrome-number

[aleattene]

Reviewers:
@micheleriva
@storrisi

I'm not sure it's the best solution.

An alternative but the less performing solution is for example this:

function isPalindrome(number) {
    let word = number.toString()
    let wordReversed = word.split("").reverse().join("")
    return (word === wordReversed)
}

Is possible to test the performance of both the solutions here:
https://replit.com/join/tvletostle-aleattene

Any other advice is always welcome.