hydra-eval-jobs: Add --dry-run option

Dependencies

• [2] 7GKAIP3V Fix build and handling of string inputs starting with a dash
• [*] 4N5APGRG * Start of a helper tool to evaluate job expressions efficiently.
• [*] SM5M2J3A Pass inputs to release expressions using -I

Change contents

• edit in src/c/hydra-eval-jobs.cc at line 14
  [5.26]

  [4.451]
  + #include "globals.hh"
• edit in src/c/hydra-eval-jobs.cc at line 253
  [2.1028]

  [2.1028]
  + else if (*arg == "--dry-run")

  + settings.readOnlyMode = true;