Add dedicated JNI bridge for ImageService

More features need to use salient images. Generalizing the bridge
that was written for bookmarks and putting it in a generally
accessible location.

IPC Context: Adding java mojo bindings to reference the client id enum
from java callers.

Test CL: https://chromium-review.googlesource.com/c/chromium/src/+/5513121

Low-Coverage-Reason: TESTS_IN_SEPARATE_CL
Bug: 338241937
Change-Id: I7c71b61ef8161c471828a139f209c200d23e0d5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5504473
Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Commit-Queue: Brandon Wylie <wylieb@google.com>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: Xi Han <hanxi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1296340}