playground: simplify various things, make setup more robust

- switch to retaining the input file tree structure
- fix flakiness related to cmd output piping by switching to multi-writer based setup
- compile everything in one go
- add a flag to configure whether service outputs (wspr/proxy/mt) are piped back to the compile server

Change-Id: I34968af72a5c5b42aef0bc9d603adbace2e1f496
20 files changed
tree: 596208eb411d8c9d4c092193c51f32c6dedff3a0
  1. lib/
  2. profiles/
  3. runtimes/
  4. security/
  5. services/
  6. tools/