[Platform] Fix the format of the API endpoints

[vpatibandla-yb]

In the platform currently, the format of the API endpoints are not consistent while accessing the appropriate resources.
For example, the API endpoint to fetch alert definitions for a universe looks like: /customers/:cUUID/alert_definitions/:uniUUID/:name. Rather it should look like /customers/:cUUID/universes/:uniUUID/alert_definitions/:name for it to make more sense and also to provide the proper authorization needed to access the resource.

Few other examples that need changes are: /customers/:cUUID/backups -> /customers/:cUUID/universes/:uniUUID/backups, /customers/:cUUID/universe_configure -> /customers/:cUUID/universes/:uniUUID/universe_configure

These changes then have to be made on the front-end side also.