Feature request: Add option to remove trailing slash

[jerelmiller]

Hey there! Thanks so much for this plugin! This plugin has been super valuable in the Gatsby websites we are building over at New Relic.

It would be amazing if we could add the option to remove the trailing slash when generating redirects. We have a situation where we need to be able to redirect from one path to another, with the new path needing query params. The query param redirect works correctly, but unfortunately the new path gets a trailing slash afterward.

For example, we need a redirect like the following:

From path: /attribute-dictionary/transaction/appname
To path: /attribute-dictionary/?event=Transaction&attribute=appName

Specifying that in the createRedirect works as we expect, but when executing in the browser, the URL becomes: /attribute-dictionary/?event=Transaction&attribute=appName/ (note the trailing slash at the end of the query params).

Thanks!