Add SearchType to OpenSharedLibraryWithExtension. This fixes a bug in SystemInfo_vulkan where we were using the System search path for the Vulkan loader when we prefer using the custom ANGLE loader. Bug: chromium:1219969 Change-Id: Iedf0fd11fe9ed8cc020b445ea9e12a7936937361 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2988791 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>