Begin to overhaul config to couple initialization logic closer to the structs themselves.

internal/configparser/modes.go

@@ -0,0 +1,19 @@
+package configparser
+
+import "slices"
+
+// validateModes checks the provided modes against a larger subset of modes (usually all defined ones)
+// and returns false if any of the modes are not defined.
+func validateModes(modes []string, allModes []string) bool {
+	if len(modes) == 0 {
+		return true
+	}
+
+	for _, mode := range modes {
+		if !slices.Contains(allModes, mode) {
+			return false
+		}
+	}
+
+	return true
+}