Canonicalize the URL to prevent duplicate PWA submissions

[dandv]

https://pwa-directory.appspot.com/pwas/5743346702090240 - 👍
https://pwa-directory.appspot.com/pwas/5667346802802688 - 👎

Query parameters like utm* should be stripped, redirects should be followed etc.

[juliantoledo]

The problem here is that the manifest URL is different, that is the current primary key for PWAs.

[juliantoledo]

We will keep https://pwa-directory.appspot.com/pwas/5667346802802688, it's the one that has a working manifest

[juliantoledo]

We will Canonicalize the URL and add it to the primary key for:
#323