Improve Build process

[cprecioso]

Build

We need to rethink and fix some parts of our build to be more robust, and to evolve rapidly.

Main issue

• Improve how we generate code (especially SDK) during wasp build #1769 (comment)

Related issues

• Build output
  • Remove the double build step (first wasp build, and then cd server && npm run build)
  • Allow having a single Docker image (client+server) as an output #3102
  • Optimize generated Dockerfile #2615
• Generated output architecture
  • Reconsider how we treat and build the SDK #2150
  • Unsplit .wasp/build and .wasp/out #3163
  • Bundle the SDK #3121
  • Optimize SDK build step #1840
  • Refactor our generated codebase #1841
• DX
  • Rename wasp build start to wasp build preview #3139
  • Explicitly type-check user code during wasp compile #1718
  • Prevent rollup errors from leaking to the client #1830
  • Solve double installation issue in restructuring #1640
  • Improve how we detect whether an NPM install is necessary #1845