sanic: url_for() doesn't return a working URI for a route with the trailing slash and strict_slashes=True

Describe the bug Say we have a route with the trailing slash and strict_slashes=True: @app.route('/endpoint/', strict_slashes=True) this way, url_for() will always trim the trailing slash, returning a non-working URL.

Code snippet

from sanic import Sanic
from sanic.response import html

app = Sanic()

# @app.route('/endpoint', strict_slashes=True)
@app.route('/endpoint/', strict_slashes=True)
async def endpoint(request):
    return html('OK')


@app.route('/')
async def index(request):
    # print(request.app.router.routes_all)
    return html('<a href="' + request.app.url_for('endpoint') + '">endpoint</a>')


if __name__ == '__main__':
    app.run(port=8000)

Expected behavior In my example, request.app.url_for('endpoint') is expected to return '/endpoint/'.

Environment (please complete the following information):

• Version 0.8.3

Additional context The current implementation of url_for() just blindly removes the trailing slash, see app.py, lines 617-618.