Align tsconfig with ts_project outputs

rules_ts validates that path-affecting TypeScript options are known to
Bazel. The checks tsconfig inherited rootDir from the shared
plugin config, which resolves outside the web package, and also
declared an IDE outDir that the ts_project rule overrides anyway.

Override rootDir locally and remove the stale outDir so the effective
tsconfig matches the package-local ts_project outputs, following the
same fix in the delete-project plugin (Ic9d6f031).

Change-Id: If378441f01e5c36b2183f115b2cb196d27eda404

web/tsconfig.json

diff --git a/web/tsconfig.json b/web/tsconfig.json
index 2e224c5..06d7107 100644
--- a/web/tsconfig.json
+++ b/web/tsconfig.json
@@ -1,8 +1,7 @@
 {
   "extends": "../../tsconfig-plugins-base.json",
   "compilerOptions": {
-    /* outDir for IDE (overridden by Bazel rule arg) */
-    "outDir": "../../../.ts-out/plugins/checks/web"
+    "rootDir": "."
   },
   "include": [
     "**/*"