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

internal/config/accounts.go

@@ -1,29 +0,0 @@
-/*
-   GoToSocial
-   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
-
-   This program is free software: you can redistribute it and/or modify
-   it under the terms of the GNU Affero General Public License as published by
-   the Free Software Foundation, either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU Affero General Public License for more details.
-
-   You should have received a copy of the GNU Affero General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*/
-
-package config
-
-// AccountsConfig contains configuration to do with creating accounts, new registrations, and defaults.
-type AccountsConfig struct {
-	// Do we want people to be able to just submit sign up requests, or do we want invite only?
-	OpenRegistration bool `yaml:"openRegistration"`
-	// Do sign up requests require approval from an admin/moderator?
-	RequireApproval bool `yaml:"requireApproval"`
-	// Do we require a reason for a sign up or is an empty string OK?
-	ReasonRequired bool `yaml:"reasonRequired"`
-}