Reorganize build steps for parallelization.

[coollog]

The new dependency graph:

Leaves:

• authPull
• authPush
• buildAppLayer (dependencies)
• buildAppLayer (classes)
• buildAppLayer (resources)

Internal Nodes:

• pullBase
  • depends on: authPull
• many of pullBaseLayer
  • each depends on: pullBase
• many of pushBaseLayer
  • each depends on: corresponding pullBaseLayer
• pushContainerConfiguration
  • depends on: buildAppLayer (dependencies), buildAppLayer (resources), buildAppLayer (classes)
• pushAppLayer (dependencies)
  • depends on: buildAppLayer(dependencies)
• pushAppLayer (resources)
  • depends on: buildAppLayer(resources)
• pushAppLayer (classes)
  • depends on: buildAppLayer(classes)
• pushImageManifest
  • depends on: every pushBaseLayer, every pushAppLayer, pushContainerConfiguration

[coollog]

Moved to https://github.com/google/jib/issues/8