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

cmd/gotosocial/server.go

@@ -0,0 +1,49 @@
+/*
+   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 main
+
+import (
+	"github.com/spf13/cobra"
+	"github.com/superseriousbusiness/gotosocial/cmd/gotosocial/action/server"
+	"github.com/superseriousbusiness/gotosocial/cmd/gotosocial/flag"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+)
+
+// serverCommands returns the 'server' subcommand
+func serverCommands() *cobra.Command {
+	serverCmd := &cobra.Command{
+		Use:   "server",
+		Short: "gotosocial server-related tasks",
+	}
+
+	serverStartCmd := &cobra.Command{
+		Use:   "start",
+		Short: "start the gotosocial server",
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			return preRun(cmd)
+		},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return run(cmd.Context(), server.Start)
+		},
+	}
+	flag.Server(serverStartCmd, config.Defaults)
+
+	serverCmd.AddCommand(serverStartCmd)
+	return serverCmd
+}