Show all frames and their local variables on assert failures [WIP]

[quinox]

• Feel free to close this PR if you're not interested: I made it for fun while playing around with gdb, just to see what's possible.
• The WIP part: I only hooked it into one of the assert failures, I think you have a few other roads how testcases could fail. I have no desire to polish this further, take it or leave it 😃

This is a separate implementation but the same idea as #135. I initially tried the other approach, ran into issues, pivoted to this solution, and once it was done I realized how I could achieve my original idea.

This implementation is cleaner but also less useful: instead of providing you with coredumps it will only show similar stack info on the terminal. It is more flexible for customization though: right now it only prints the frame name + local variables but you can show whatever you want.

---

This PR will show you stack information when an assertion failure is triggered. An example output:

INIT: testStringDistances
RUN: testStringDistances
- [trigger_gdb_if_attached]
  - [fmq_assert]
    b = false (bool)
    failmsg = 0x55555594ddf2 "Values aren't the same" (const char *)
    actual = 0x5555559511c8 "distanceBetweenStrings(\"\", \"whoopsie\")" (const char *)
    expected = 0x5555559511b8 "(unsigned int)0" (const char *)
    file = 0x555555950fd8 "/home/quinox/projects/FlashMQ/FlashMQTests/configtests.cpp" (const char *)
    line = 123 (int)
    - [fmq_compare<unsigned int, unsigned int>]
      t1 = @0x7fffffffdd58 (const unsigned int &)
      t2 = @0x7fffffffdd5c (const unsigned int &)
      actual = 0x5555559511c8 "distanceBetweenStrings(\"\", \"whoopsie\")" (const char *)
      expected = 0x5555559511b8 "(unsigned int)0" (const char *)
      file = 0x555555950fd8 "/home/quinox/projects/FlashMQ/FlashMQTests/configtests.cpp" (const char *)
      line = 123 (int)
      - [MainTests::testStringDistances]
        this = 0x7fffffffe120 (MainTests * const)
FAIL: 'Values aren't the same', distanceBetweenStrings("", "whoopsie") != (unsigned int)0
 in /home/quinox/projects/FlashMQ/FlashMQTests/configtests.cpp, line 123
FAIL: testStringDistances

Tests run: 1. Passed: 0. Failed: 1 (of which 0 exceptions). Total assertions: 1.


Failed tests:
 - testStringDistances

TESTS FAILED
[Inferior 1 (process 13425) exited with code 01]
Bummer


Tail of stderr:

[halfgaar]

Hey, triggering gdb when attached is cool. It's always been annoying when getting an assert fail and even setting a breakpoint an trying again (assuming the case is reproducible), if the variables are temporaries, you don't see them.

I see that there are also some tricks to do the same for exceptions. That may be useful too. In C# that was always easy, but never got around to seeing if I could do that here. The main context where that is useful, is the 'waitForCondition' line in tests, although I can at least also wrap that around a macro that mentions line number and file.