Retry build_daemon state file reads

[grouma]

Closes #2210

Changes:

• Add retry logic to reading the various state files, e.g. portFile.
• Update test daemon to better mimic actual implementations i.e. read version file
• Add test to ensure there is no race condition
• Rev version
  • Note that this isn't technically a breaking change as we haven't exposed the src/daemon.dart yet but it should be treated as one.