Refactor Package structure

This commit cleans up the package structure, to make two new top-level
packages `internal` (for internal-use packages) and `pkg` (for general
shared utility code).

component/sql/sql.go

@@ -1,38 +0,0 @@
-package sql
-
-import (
-	"context"
-	"embed"
-	"io/fs"
-	"time"
-
-	"github.com/FAU-CDI/wisski-distillery/component"
-)
-
-type SQL struct {
-	component.ComponentBase
-
-	ServerURL string // upstream server url
-
-	PollContext  context.Context // context to abort polling with
-	PollInterval time.Duration   // duration to wait for during wait
-}
-
-func (SQL) Name() string {
-	return "sql"
-}
-
-//go:embed all:stack
-var resources embed.FS
-
-func (ssh SQL) Stack() component.Installable {
-	return ssh.ComponentBase.MakeStack(component.Installable{
-		Resources:   resources,
-		ContextPath: "stack",
-
-		MakeDirsPerm: fs.ModeDir | fs.ModePerm,
-		MakeDirs: []string{
-			"data",
-		},
-	})
-}