fix(lifecycle): cleanup lifecycle

- removes unwieldy SkipUpdate return value in favor of errors.Is
- generalizes the code for all four phases
- allows timeout to be defined for all phases
- enables explicit unit in timeout label values (in addition to implicit minutes)

pkg/types/lifecycle.go

@@ -0,0 +1,27 @@
+package types
+
+import "fmt"
+
+type LifecyclePhase int
+
+const (
+	PreCheck LifecyclePhase = iota
+	PreUpdate
+	PostUpdate
+	PostCheck
+)
+
+func (p LifecyclePhase) String() string {
+	switch p {
+	case PreCheck:
+		return "pre-check"
+	case PreUpdate:
+		return "pre-update"
+	case PostUpdate:
+		return "post-update"
+	case PostCheck:
+		return "post-check"
+	default:
+		return fmt.Sprintf("invalid(%d)", p)
+	}
+}