global: Rename with normal TypeScript module extension.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

tools/test-js-with-node

@@ -112,7 +112,7 @@ EXEMPT_FILES = make_set(
         "web/src/flatpickr.ts",
         "web/src/gear_menu.js",
         "web/src/giphy.js",
-        "web/src/global.d.ts",
+        "web/src/global.ts",
         "web/src/hash_util.ts",
         "web/src/hashchange.js",
         "web/src/hbs.d.ts",

web/src/global.ts

@@ -25,6 +25,7 @@ type JQueryIdleOptions = Partial<{
 declare global {
     let zulip_test: any; // eslint-disable-line @typescript-eslint/no-explicit-any
 
+    // eslint-disable-next-line @typescript-eslint/no-namespace
     namespace JQueryValidation {
         // eslint-disable-next-line @typescript-eslint/consistent-type-definitions
         interface ValidationOptions {