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).

internal/component/self/self.go

@@ -0,0 +1,42 @@
+package self
+
+import (
+	"embed"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/component"
+)
+
+type Self struct {
+	component.ComponentBase
+}
+
+func (Self) Name() string {
+	return "self"
+}
+
+//go:embed all:stack
+//go:embed self.env
+var resources embed.FS
+
+func (self Self) Stack() component.Installable {
+	// TODO: Move me into config!
+	TARGET := "https://github.com/FAU-CDI/wisski-distillery"
+	if self.Config.SelfRedirect != nil { // TODO: move to config!
+		TARGET = self.Config.SelfRedirect.String()
+	}
+
+	return self.ComponentBase.MakeStack(component.Installable{
+		Resources: resources,
+
+		ContextPath: "stack",
+		EnvPath:     "self.env",
+
+		EnvContext: map[string]string{
+			"VIRTUAL_HOST":      self.Config.DefaultHost(),
+			"LETSENCRYPT_HOST":  self.Config.DefaultSSLHost(),
+			"LETSENCRYPT_EMAIL": self.Config.CertbotEmail,
+			"TARGET":            TARGET,
+			"OVERRIDES_FILE":    self.Config.SelfOverridesFile,
+		},
+	})
+}