Fix for disable_timer_outputs

[m-bossart]

• Fixes a bug related to an unknown variable (BUILD_PROBLEMS_TIMER).
• Automatically enables the BUILD_TIMER at the start of building the simulation if disable_timer_outputs == false .
• Adds a test for the case where disable_timer_outputs == true.

[codecov]

Codecov Report

Merging #346 (471de96) into main (5796411) will increase coverage by 0.43%.
Report is 1 commits behind head on main.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #346      +/-   ##
==========================================
+ Coverage   86.99%   87.42%   +0.43%     
==========================================
  Files          65       65              
  Lines        8664     8619      -45     
==========================================
- Hits         7537     7535       -2     
+ Misses       1127     1084      -43     

Flag	Coverage Δ
unittests	87.42% <100.00%> (+0.43%)	⬆️

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

Files Changed	Coverage Δ
src/base/simulation.jl	93.30% <100.00%> (+1.39%)	⬆️

... and 4 files with indirect coverage changes

[github-actions]

Performance Results

Version	Precompile Time
Main	5.223912328
This Branch	5.238405931

Version	Run Time
Main-Build ResidualModel	13.340940484
Main-Execute ResidualModel	34.662727625
Main-Build MassMatrixModel	1.147260331
Main-Execute MassMatrixModel	361.503381802
This Branch-Build ResidualModel	13.070988115
This Branch-Execute ResidualModel	35.820242166
This Branch-Build MassMatrixModel	1.216337583
This Branch-Execute MassMatrixModel	363.821898643

ResidualModel and MassMatrixModel performance results should be compared between versions and not between models due to the execution order of the tests