Implement pseudo plain parsing

__tests__/pseudoplain-gmail-gmail.test.ts

+import { EMAIL_VENDORS } from "../src";
+
+const path = require("path");
+import { describe } from "@jest/globals";
+import { createDescribePseudoPlainTestCases } from "./utils";
+
+const TESTS_GLOBAL_PATH = "/files/gmail-gmail";
+const testsPath = path.resolve(__dirname, `.${TESTS_GLOBAL_PATH}`);
+
+describe("[Pseudo PLAIN] GMail-GMail", () => {
+  const describeFunction = createDescribePseudoPlainTestCases(
+    testsPath,
+    EMAIL_VENDORS.GMAIL
+  );
+
+  describe("One", describeFunction("one"));
+});