Add fail_fast runtime error policy

[tcbrindle]

This adds a new fail_fast runtime error policy to go with our existing terminate and unwind policies.

As the name suggests, fail_fast is intended to tear down the process in the fastest way possible should a runtime error occur. It uses __builtin_trap() on GCC and Clang, the __fastfail() intrinsic on MSVC, and otherwise falls back to std::abort(). Unlike the terminate policy, it never attempts to print a message to stderr.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.81%. Comparing base (291df6d) to head (c08e6d6).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #210      +/-   ##
==========================================
- Coverage   98.81%   98.81%   -0.01%     
==========================================
  Files          69       69              
  Lines        2534     2523      -11     
==========================================
- Hits         2504     2493      -11     
  Misses         30       30              

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