Add a "shortlink" for projects

[nlhkabu]

From user testing:

When viewing projects on PyPI, some users type the URL directly if they know the project name.

We should create a shortlink likepypi.org/p/myproject which would redirect to pypi.org/projects/myproject

cc @di for feedback / guidance.

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[di]

Going to remove the "good first issue" label from this. IMO while this would be nice, it's not likely to happen.

We have a number of other routes that sit at the top level path here, and this would make packages conflict with them, e.g. would https://pypi.org/help/ go to our "Help" page (as it does now) or to the help project (currently at https://pypi.org/project/help/)?

We would need to 'audit' the existing routes for conflicting projects and either rename our routes or "reserve" the project name for our own routes.

This would also make adding new routes harder in the future, because we'd need to go through the same process, rather than just adding it as we do now.

[paternal]

What about a short route? E.g. https://pypi.org/p/foobar which would replace, or be an alias to https://pypi.org/project/foobar . It would be a shorter URL to type directly, while not messing up "non project" routes (like https://pypi.org/help).

[dstufft]

I'd be fine with a shorter router as an alias. I don't think we gain much by making it the canonical location, but a blanket redirect of /p/ to /project/ seems like it'd be fine, and let people type out something shorter.

[di]

Sounds good to me, this is probably a "good first issue" then. I've updated the title/description/labels accordingly.