build: Enable tsec checks for critical packages. (#43108)

tsec is a static analyzer that discovers Trusted Types violations.
Deploy tsec to make sure there will be no TT regression in several
critical packages, including core, platform-browser, platform-server
and their dependencies. Existing violations have been reviewed and
exempted in packages/tsec-exemption.json. Future changes to the
exemption list requires security review.

PR Close #43108

packages/core/tsconfig-tsec.json

@@ -0,0 +1,15 @@
+/** For building //packages/core. */
+{
+  "extends": "../tsconfig-tsec-base.json",
+  "compilerOptions": {
+    "outDir": ".tsec"
+  },
+  "include": [
+    "*.ts",
+    "src/**/*.ts",
+    "../*.d.ts"
+  ],
+  "references": [
+    {"path": "../zone.js/lib/tsconfig-tsec.json"}
+  ]
+}