Allow users to reference the alias field from web-features

[jcscottiii]

Sometimes features are renamed and the old id is moved to the alias field.

A user should be able to go to https://webstatus.dev/features/<alias> and be redirected to the page for the main id.

cc: @foolip

[foolip]

Yep, redirects is what I had in mind with the alias field.

[foolip]

That being said, I guess that zero people depend on the aliases that we have so far. It might be a good idea to just remove all of them and not claim those identifiers forever.

I'm sure we'll eventually need to support redirects for mistakes and merged features, however.

[foolip]

We deleted this field in web-platform-dx/web-features#1450 ahead of the 1.0 release. Starting from a clean slate. We might need it again in the future, but it's OK to close this issue for now.