feat: WaveEquation : new acoustic gradient formulation

[rmadec-cs]

New Acoustic gradient formulation with respect to parameters Kappa=1/rho*c2 and Buoyancy=1/rho replacing old gradient formulation with respect to velocity c

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 77.00535% with 43 lines in your changes missing coverage. Please review.

Project coverage is 57.11%. Comparing base (dc6a6be) to head (d97241d). Report is 59 commits behind head on develop.

Files with missing lines	Patch %	Lines
...condOrderEqn/isotropic/AcousticWaveEquationSEM.cpp	23.52%	26 Missing :warning:
.../sem/acoustic/shared/AcousticMatricesSEMKernel.hpp	0.00%	17 Missing :warning:

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3361      +/-   ##
===========================================
+ Coverage    57.05%   57.11%   +0.06%     
===========================================
  Files         1150     1151       +1     
  Lines        99304    99454     +150     
===========================================
+ Hits         56660    56808     +148     
- Misses       42644    42646       +2     

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[sframba]

@acitrain @rrsettgast @CusiniM @wrtobin @corbett5 does any of you have time for a review of this PR? Thanks!

[acitrain]

Hi @rrsettgast,

Can you please final check this PR? Everything is good rebaseline included

Thank you !

[rrsettgast]

@rmadec-cs @acitrain baselines got updated under this. Gonna have to put baselines back to develop...run integratedTests again...then set the baseline to the new hash....but wait until you are first in line in the queue...otherwise you may have to do it again!

[paveltomin]

@rmadec-cs @acitrain baselines got updated under this. Gonna have to put baselines back to develop...run integratedTests again...then set the baseline to the new hash....but wait until you are first in line in the queue...otherwise you may have to do it again!

done

[rrsettgast]

@paveltomin I took this out of the queue due to @CusiniM request.