feat: Allow the build to be configured in "fail on error" mode

[HadrienG2]

This PR enables the Acts logger to be configured in such a way that all log messages above a certain debug level (typically WARNING or ERROR) cause an exception to be thrown.

This is useful because Acts has a certain number of non-fatal error scenarios, which should not crash real-world physics reconstruction but indicate suspicious behavior that we will usually want to catch in automated testing (where we can control the inputs and make sure that non-fatal errors do not occur "by chance").

Throwing an exception on logging did not compose well with the Logger::OutStream mechanism, which would emit logs in its destructor, so after some discussion with @paulgessinger I decided to fix this by removing this mechanism and reworking the logger API in a much simpler direction. After all, logging is not meant to be fast, so passing logs as std::strings is okay as long as there's a way for the caller to avoid generating the std::string when it's not going to be printed.

Since Logger is not documented to be part of the public Acts API, I do not consider this API rework to be a breaking change.

Fixes #482 .

[HadrienG2]

This PR does not yet enable the newly introduced functionality in CI for two reasons:

1. Stacking CI and code changes in a single PR seems counter to the spirit of using semantic labels for PRs. So this should probably be taken care of in a follow-up PR with a "chore" label.
2. It would lead to a red CI due to a previously uncaught bug in AtlasStepperTests, which is caught by the new mechanism, and which I don't know how to fix. The symptoms look suspiciously similar to Fatal Error in local-to-global transformations #579 .

[HadrienG2]

@paulgessinger It looks like the macOS build is misbehaving. I think we already observed a similar issue before?

[codecov]

Codecov Report

Merging #687 (2350d1a) into master (5c6bbbb) will increase coverage by 0.03%.
The diff coverage is 16.98%.

@@            Coverage Diff             @@
##           master     #687      +/-   ##
==========================================
+ Coverage   49.00%   49.03%   +0.03%     
==========================================
  Files         331      331              
  Lines       16549    16549              
  Branches     7723     7725       +2     
==========================================
+ Hits         8110     8115       +5     
- Misses       3009     3013       +4     
+ Partials     5430     5421       -9     

Impacted Files	Coverage Δ
Core/include/Acts/Propagator/Navigator.hpp	57.54% <0.00%> (-1.09%)	⬇️
Core/src/Geometry/TrackingVolume.cpp	43.36% <0.00%> (+1.30%)	⬆️
Core/src/Utilities/Logger.cpp	44.00% <0.00%> (+8.00%)	⬆️
Core/include/Acts/Utilities/Logger.hpp	61.22% <47.36%> (-2.42%)	⬇️
Core/src/Geometry/CylinderVolumeHelper.cpp	29.25% <0.00%> (-0.16%)	⬇️
...e/include/Acts/Vertexing/IterativeVertexFinder.ipp	22.91% <0.00%> (+1.66%)	⬆️
Core/include/Acts/Geometry/SurfaceArrayCreator.hpp	41.81% <0.00%> (+1.81%)	⬆️

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[paulgessinger]

LGTM, let's override the coverage report.