Refactor prefixIds (#1561)

Ref https://github.com/svg/svgo/issues/1499

- migrated to visitor plugin api
- covered with tsdoc
- made the plugin idempotent as requested a few times
  Now even manually running svgo a few times will not duplicate
  prefix in ids and classes
- run each plugin test twice to see which plugin need to run many times
  ideally idempotent plugins will allow to get rid of multipass option in v3

lib/types.ts

@@ -71,7 +71,16 @@ export type Visitor = {
   root?: VisitorRoot;
 };
 
-export type Plugin<Params> = (root: XastRoot, params: Params) => null | Visitor;
+export type PluginInfo = {
+  path?: string;
+  multipassCount: number;
+};
+
+export type Plugin<Params> = (
+  root: XastRoot,
+  params: Params,
+  info: PluginInfo
+) => null | Visitor;
 
 export type Specificity = [number, number, number, number];