Swagger page redirect isn't working

Problem: https://SERVERIP/swagger/ working but https://SERVERIP/swagger is not

WE need to have some "redirect" to let both URL to work

STR:

1. Install latest PMM2 server
2. Open URL
3. Log in to Grafana with username=admin and password=admin
4. Open URL/swagger

Given result: Empty page is displayed and there is an error:

URL/swagger/ works OK, and before URL/swagger redirects to /swagger/, so the problem in redirecting

Expected result:

Swagger is displayed

Success criteria:

1. Opening /swagger should display the page
2. Opening /swagger.json should display the swagger json object
3. Opening /swagger/swagger.json should redirect to /swagger.json and display the swagger json object
4. Opening /swagger/ should redirect to /swagger and then display the page
5. Opening /swagger/<anything here> should redirect to /swagger and then display the page
6. If the user is unauthenticated, opening /swagger should display the page (as it does currently)
7. Everything above should work the same in the dev-container (special attention to this swagger test)