Refactor preprocessors module

src/codecs/preprocessors.ts

@@ -0,0 +1,15 @@
+import { QuantizeOptions, defaultOptions as quantizerDefaultOptions } from './imagequant/quantizer';
+
+interface Enableable {
+  enabled: boolean;
+}
+export interface PreprocessorState {
+  quantizer: Enableable & QuantizeOptions;
+}
+
+export const defaultPreprocessorState = {
+  quantizer: {
+    enabled: false,
+    ...quantizerDefaultOptions,
+  },
+};