Given a FSM, generate parallel tests.

[jeffh]

Each API call is assumed atomic.

• [x] Add Parallel Testing to CLI & CI (to fix CI failures)
• [x] Automate providing the FoxlingCompiler Plugin for Releases.
• [x] Documentation how parallel testing works in Fox
  • [x] Lock implementations overridden
  • [x] Libraries that are safe to use (aka - no direct kernel threads code)
  • [x] Testing with and without the cooperative scheduler
  • [x] Testing with Foxling Compiler
  • [x] Current limitations in implementation for automatic thread yielding (e.g. - no Swift support, expressions replaced, number of concurrent commands, etc.)
• [x] Document how to develop / compile Foxling
• [ ] Verify: parallel testing does not work on iOS devices?
• [ ] Document if parallel test does not work on iOS devices.
• [x] Remove hardcoded paths in Foxling
• [ ] Finish overriding mach semaphores.
• [ ] Alcatraz Support for Foxling

Bonus:

• [ ] Good ways of testing the compiler besides End-to-End?
• [ ] Configuring the plugin to automatically refer to its internal copy of the Foxling compiler.

Finalize:

• [ ] Audit APIs that are alpha
• [ ] Audit documentation that marks alpha APIs
• [ ] Grammer / editing check of documentation.
• [ ] Create and link issues mentioned in the documentation.

Things to consider in other PR/issues:

• Dead-lock detection / timeout runs
• More rewriting rules for Foxling
• Non-brute-force linearizable verifier.