Get specific path from `edgedb info`

[colinhacks]

It would make it easier to document/explain certain things if there was a way to get a particular path from edgedb info.

Currently:

$ edgedb info 
[2022-08-16T19:02:15Z WARN  edgedb::version_check] Newer version of edgedb tool exists 2.0.4+a7fc49b (current 2.0.0)
EdgeDB uses the following local paths:
┌───────────────┬────────────────────────────────────────────────────────────┐
│ Cache         │ /Users/colinmcd94/Library/Caches/edgedb/                   │
│ Config        │ /Users/colinmcd94/Library/Application Support/edgedb/      │
│ Custom Binary │ /Users/colinmcd94/Documents/edgedb/core/edb/cli/edgedb     │
│ Data          │ /Users/colinmcd94/Library/Application Support/edgedb/data/ │
│ Service       │ /Users/colinmcd94/Library/LaunchAgents/                    │
└───────────────┴────────────────────────────────────────────────────────────┘

Proposed API - inspired by git config

$ edgedb info --get config-dir
/Users/colinmcd94/Library/Application Support/edgedb/

This makes it easier to explain things like credentials/projects/etc. e.g. https://discord.com/channels/841451783728529451/841451783728529454/1008775485741875220

It would be great to be able to give users single commands like "Get your credentials file by running cat $(edgedb info --get config-path)/credentials/my_instance.json

The current paths can be mapped like so:

Syntax	Description
Cache	cache-dir
Config	config-dir
Custom Binary	cli-dir
Data	data-dir
Service	service-dir