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/web/thread.go

@@ -19,10 +19,13 @@
 package web
 
 import (
-	"github.com/sirupsen/logrus"
 	"net/http"
 
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/viper"
+
 	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 )
 
@@ -51,7 +54,8 @@ func (m *Module) threadTemplateHandler(c *gin.Context) {
 		return
 	}
 
-	instance, err := m.processor.InstanceGet(ctx, m.config.Host)
+	host := viper.GetString(config.Keys.Host)
+	instance, err := m.processor.InstanceGet(ctx, host)
 	if err != nil {
 		l.Debugf("error getting instance from processor: %s", err)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal server error"})