Allow an array of strings in <Route path>

This is a follow-up from #5393.

It would be nice if <Route path> could accept an array of strings instead of a single string. This would make it possible to render the same <Route> element at multiple different URLs as suggested here.

The reason #5393 was not merged is because there was a problem with the way the code worked with respect to relative routes. When this work is done, match.path should still be a string, not an array.

[kyleramirez]

What needs to be done to remove this prop-types warning?

In the meantime, I patch this in my own codebase by overriding the default prop types.

For those of you reading this, here is what I do:

import { Route } from "react-router-dom"
import PropTypes from "prop-types"

Route.propTypes = {
  computedMatch: PropTypes.object,
  path: PropTypes.oneOfType([PropTypes.array, PropTypes.string]),
  exact: PropTypes.bool,
  strict: PropTypes.bool,
  sensitive: PropTypes.bool,
  component: PropTypes.func,
  render: PropTypes.func,
  children: PropTypes.oneOfType([PropTypes.func, PropTypes.node]),
  location: PropTypes.object
}

[mjackson]

Closed by #5889.