Simplify our "advanced" proxy

Created by: Timer

I think we made a mistake when we added advanced proxy configuration in 1.x.

It's poor DX imo, and has caused numerous issues (I'm too lazy to search for them 😝). I mean look at this monstrosity. Yuck!

Note: this is not an attack against the contributor of this change. We are very grateful for the contribution and it has served us well. 😄

I propose we support the simplest of configurations:

1. Our default, simple behavior which works for many cases:

     "proxy": "http://localhost:4000",

2. An advanced case, which uses globs and proxies in 100% of cases (no heuristic):

     "proxy": [
       { "match": ["api/**/*", "!api/ws/*"], "target": "http://localhost:4000" },
       { "match": "api/ws/*", "target": "ws://localhost:4000" },
       { "match": "api2/**/*", "target": "http://localhost:4001" }
     ]

   or

     "proxy": [
       [["api/**/*", "!api/ws/*"], "http://localhost:4000"],
       ["api/ws/*", "ws://localhost:4000"],
       ["api2/**/*", "http://localhost:4001"]
     ]

In the "advanced" case, we don't need to set ssl -- check for https:// over http://. We don't need to set ws, check for ws://; etc. Other features (e.g. url rewrites) should never happen at the client layer because this doesn't translate to production (it's leaky domain logic).

Thoughts?

We can add some code to auto-migrate old usage and remove it in v3.