[vtadmin-web] Add React Router + a skeleton /debug page to VTAdmin

[doeg]

Signed-off-by: Sara Bee 855595+doeg@users.noreply.github.com

Description

Adds react router + a /debug page. Another tiny PR pulled out of a bigger branch.

For a little context, I plan to co-opt the debug page as an informal style guide as I add all of the components in the Figma spec. (In the past, I've used Storybook for this, but I think that's way overkill for what we need for the near future.)

No one asked, but my $0.02 anyway (haha). I personally prefer ui-router over React Router. (I think it's more straightforward.) That said, the ui-router documentation is very painful to navigate. React Router has better documentation and I think it's fair to that it's still the industry (or at least React!) standard, so I think it's a better + more approachable choice for an open source project.

Looks great so far, right? :D (Just kidding.)

Related Issue(s)

N/A

Checklist

• Should this PR be backported?
• Tests were added or are not required N/A
• Documentation was added or is not required N/A

Deployment Notes

Impacted Areas in Vitess

Components that this PR will affect:

• Query Serving
• VReplication
• Cluster Management
• Build
• VTAdmin

[ajm188]

lgtm!