refactor: explicitly ensure ngDevMode types are available (#61365)

This commit adds an import to the `ng_dev_mode.ts` file that augments
`global` to have types for `ngDevMode`.

Notably this change is currently not needed because the file is loaded
by `ts_library` through `tsconfig#files`— but in a separate PR we are
switching the target to `ts_project` which no longer loads all Bazel
dependency files via `tsconfig#files`; resulting in the ambient types no
longer magically being available.

PR Close #61365

packages/core/primitives/event-dispatch/src/event_dispatcher.ts

@@ -13,6 +13,9 @@ import {isCaptureEventType} from './event_type';
 import {UnrenamedEventContract} from './eventcontract';
 import {Restriction} from './restriction';
 
+// Necessary to make the `ngDevMode` global types available.
+import '../../../src/util/ng_dev_mode';
+
 /**
  * A replayer is a function that is called when there are queued events, from the `EventContract`.
  */