PR/Issue Dashboard

[dougch]

Resolved issues:

#2293

Description of changes:

Similar to s2n-tls Issue/PR dashboard, but with some quic specific searches.

Call-outs:

• Labels are different from tls, things like stale and do_not_merge don't exist
• s2n-quic uses dependabot, which deserves to be excluded from most of these queries, but also with a dedicated stat
• we're not labeling internal vs external contributors, I'm hoping to come up with a better way to do this before add to quic.
• The dashboard css isn't managed by the action and is directly checked into the gh-pages branch

Testing:

How is this change tested: forked repo https://dougch.github.io/s2n-quic/dashboard/

Is this a refactor change? If so, how have you proved that the intended behavior hasn't changed? -->

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[camshaft]

One thing that would be helpful is having the number of issues without an assigned priority:

https://github.com/aws/s2n-quic/issues?q=is%3Aissue+is%3Aopen+-label%3Apriority%2Flow+-label%3Apriority%2Fmedium+-label%3Apriority%2Fhigh+-label%3AMSRV

[dougch]

One thing that would be helpful is having the number of issues without an assigned priority:

https://github.com/aws/s2n-quic/issues?q=is%3Aissue+is%3Aopen+-label%3Apriority%2Flow+-label%3Apriority%2Fmedium+-label%3Apriority%2Fhigh+-label%3AMSRV

Added