[AsyncFunctionHandler] Add exception handling

[saikishor]

Right now, the async function handler doesn't work well when the exceptions are then in the callback and this might be an issue that we might face in the short term.

This PR addresses this issue by handling the exceptions and throw in the thread that calls trigger_async_callback, so that the main thread is aware of the exception and handle it properly

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.26%. Comparing base (7bd84f6) to head (bf05c0b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #172      +/-   ##
==========================================
+ Coverage   80.39%   81.26%   +0.87%     
==========================================
  Files           8        8              
  Lines         306      315       +9     
  Branches       53       54       +1     
==========================================
+ Hits          246      256      +10     
  Misses         25       25              
+ Partials       35       34       -1     

Flag	Coverage Δ
unittests	81.26% <100.00%> (+0.87%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
include/realtime_tools/async_function_handler.hpp	91.02% <100.00%> (+2.61%)	⬆️