Add Routify config option to preserve/strip/force the trailing slash on urls

[jdkdev]

Describe the feature

We are starting to get some bigger clients that are tracking url and clicks in Google anayltics like hawks. And sometimes it's the direct link they see /my-page/ but then if the user clicks around the SPA and take action it could fire with /my-page as the event url....causing split metrics ..

and spank creates the /my-page/index.html so Cloudflare serves that up as /my-page/ as the 200 and /my-page as the 308 redirect.

Suggestion: maybe trailing slashes should have three options then: force, strip, preserve

Reference:
https://github.com/roxiness/routify/blob/next/lib/runtime/Router/Router.js#L329

Examples

/my-page/ loads and then url updates to /my-page, with this option it would stay /my-page/