Implement Cobra CLI tooling, Viper config tooling (#336)

* start pulling out + replacing urfave and config

* replace many many instances of config

* move more stuff => viper

* properly remove urfave

* move some flags to root command

* add testrig commands to root

* alias config file keys

* start adding cli parsing tests

* reorder viper init

* remove config path alias

* fmt

* change config file keys to non-nested

* we're more or less in business now

* tidy up the common func

* go fmt

* get tests passing again

* add note about the cliparsing tests

* reorganize

* update docs with changes

* structure cmd dir better

* rename + move some files around

* fix dangling comma

docs/configuration/general.md

@@ -14,12 +14,12 @@ The only things you *really* need to set here are `host`, which should be the ho
 # String. Log level to use throughout the application. Must be lower-case.
 # Options: ["trace","debug","info","warn","error","fatal"]
 # Default: "info"
-logLevel: "info"
+log-level: "info"
 
 # String. Application name to use internally.
 # Examples: ["My Application","gotosocial"]
 # Default: "gotosocial"
-applicationName: "gotosocial"
+application-name: "gotosocial"
 
 # String. Hostname that this server will be reachable at. Defaults to localhost for local testing,
 # but you should *definitely* change this when running for real, or your server won't work at all.
@@ -38,7 +38,7 @@ host: "localhost"
 # DO NOT change this after your server has already run once, or you will break things!
 # Examples: ["example.org","server.com"]
 # Default: ""
-accountDomain: ""
+account-domain: ""
 
 # String. Protocol to use for the server. Only change to http for local testing!
 # This should be the protocol part of the URI that your server is actually reachable on. So even if you're
@@ -55,7 +55,7 @@ protocol: "https"
 # you have specific networking requirements.
 # Examples: ["0.0.0.0", "172.128.0.16", "localhost", "[::]", "[2001:db8::fed1]"]
 # Default: "0.0.0.0"
-bindAddress: "0.0.0.0"
+bind-address: "0.0.0.0"
 
 # Int. Listen port for the GoToSocial webserver + API. If you're running behind a reverse proxy and/or in a docker,
 # container, just set this to whatever you like (or leave the default), and make sure it's forwarded properly.
@@ -71,6 +71,6 @@ port: 8080
 # or the gateway of the docker network, and/or the address of the reverse proxy (if it's not running on the host network).
 # Example: ["127.0.0.1/32", "172.20.0.1"]
 # Default: ["127.0.0.1/32"] (localhost)
-trustedProxies:
+trusted-proxies:
   - "127.0.0.1/32"
 ```