Alternative take on an e2e conformance test view + UA filtering support in audit-log-review

[Katharine]

This PR, inspired by conversations with @spiffxp, explores an alternative take on viewing the e2e conformance API coverage, presenting a heatmap-style table that one can use to drill down. It also adds importing of User-Agent information from the audit log, which is used for filtering purposes, and changes the import to consider "watch" to be separate from "get".

Other changes:

• the driver script now always spins up a webserver, which serves the conformance dashboard view introduced here.
• You now use python import.py <path to audit log> to do an import.
• The data format in the internal API used is now an array of JSON objects instead of an array of arrays with headers, which is less bandwidth efficient but probably not in a way that really matters here.
• There is a bug (0.7.4/0.7.5 breaks queries using the in operator to test membership of another query result ponyorm/pony#373) breaking us under some versions of ponyorm, so I have made the version constraint there more specific.
• Only data from stable APIs is now displayed

This PR fairly obviously does several things. However, given the code isn't terribly large (a substantial amount of it is copying existing code from this repo) and is entirely interdependent, I'm not sure if it would be very useful to break it up further.

Here are a couple of screenshots:

[hh]

Thanks @Katharine ! Great work.

I've been a bit heads down in gingko libaries, but I'd be up for a pair session in the next day or so to go through this.

Ping me here or on the kubernetes slack.

[Katharine]

Following on from working with @hh yesterday, I have rebased this PR to more appropriately create dev/e2e-coverage-view, instead of radically altering dev/audit-log-review.

[hh]

I like this view, should should have some new data (per test User Agents) by the end of the day.