Allow native bridge to work without a code cache

In isolatedProcess, the app_code_cache_dir is not needed
for native bridge. This commit allows native bridge to work
without a code cache in isolatedProcess.

Change-Id: I8580268d5ec6ca8d44e4500c3fafe10408e1e0d3
Signed-off-by: jgu21 <jinghui.gu@intel.com>