Add counter documentation/examples. Tweak counter triggers/actions in automod.

Rename change_counter automod action to add_to_counter,
add set_counter action, rename counter trigger to counter_trigger.

backend/src/plugins/Automod/triggers/counterTrigger.ts

@@ -0,0 +1,52 @@
+import * as t from "io-ts";
+import { automodTrigger } from "../helpers";
+import { consumeIgnoredRoleChange } from "../functions/ignoredRoleChanges";
+import { CountersPlugin } from "../../Counters/CountersPlugin";
+import { tNullable } from "../../../utils";
+
+// tslint:disable-next-line
+interface CounterTriggerResult {}
+
+export const CounterTrigger = automodTrigger<CounterTriggerResult>()({
+  configType: t.type({
+    counter: t.string,
+    trigger: t.string,
+    reverse: tNullable(t.boolean),
+  }),
+
+  defaultConfig: {},
+
+  async match({ triggerConfig, context, pluginData }) {
+    if (!context.counterTrigger) {
+      return;
+    }
+
+    if (context.counterTrigger.counter !== triggerConfig.counter) {
+      return;
+    }
+
+    if (context.counterTrigger.trigger !== triggerConfig.trigger) {
+      return;
+    }
+
+    const reverse = triggerConfig.reverse ?? false;
+    if (context.counterTrigger.reverse !== reverse) {
+      return;
+    }
+
+    return {
+      extra: {},
+    };
+  },
+
+  renderMatchInformation({ matchResult, pluginData, contexts, triggerConfig }) {
+    let str = `Matched counter trigger \`${contexts[0].counterTrigger!.prettyCounter} / ${
+      contexts[0].counterTrigger!.prettyTrigger
+    }\``;
+    if (contexts[0].counterTrigger!.reverse) {
+      str += " (reverse)";
+    }
+
+    return str;
+  },
+});