Vulkan: Pass shader module map to init pipelines. Instead of pulling out the shader modules from the shader map when we start the call chain, pull them out right in the init call. This saves a bunch of boilerplate code. Refactoring change only. Bug: angleproject:6566 Change-Id: Ib8d79bd7284d7ddb83522270f3d4df9086ab7300 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3221134 Reviewed-by: Tim Van Patten <timvp@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>