Js doc overloads

[apendua]

Fixes #25590

Since there was no final consensus, I ended up using a new @overload tag to ensure backwards compatibility, e.g.

/**
 * @overload
 * @param {number} x
 * @returns {'number'}
 */
/**
 * @overload
 * @param {string} x
 * @returns {'string'}
 */
/**
 * @overload
 * @param {boolean} x
 * @returns {'boolean'}
 */
/**
 * @param {unknown} x
 * @returns {string}
 */
function typeName(x) {
  return typeof x;
}

I would be happy to modify the implementation if someone suggests a better approach.

[ghost]

All CLA requirements met.

[ValeTheVioletMote]

Looking forward to this!

[apendua]

Closing this PR in favor of: https://github.com/microsoft/TypeScript/pull/51234