Refactor laser implementation

[steindev]

This refactoring straightens the implementation of laser profiles and removes confusing terms being added and later subtracted.

Major changes are:

• redefinition of the internal coordinate system: The focus becomes the actual 'origin' of the coordinate system, while the origin variable refers to the position on the Huygens surface where the field needs to be evaluated in order to feed it into the simulation
  => This allows to implement expressions for laser fields as they are printed in publications and text books w/o additional phase and envelope terms
• the GaussianPulse can have different waist sizes along the transverse directions now
• the pulse-front tilt feature of the GaussianPulse is removed, because it is unknown how pulse-front tilted Laguerre-Gaussian pulses propagate (our old implementation fed some field in the simulation which propagated physically toward the focus, but this (most probably) did not correspond to the expectation for the in-focus field)
  => For pulse-front tilted standard Gaussian pulses the DispersivePulse can and should be used
• dispersions in the DispersivePulse are applied along the polarization axis, while the other transverse axis is dispersion-free

Draft status of this PR will be removed when the following action items are performed

• GaussianPulse:
  • Compile test simulation w/ and w/o Laguerre modes and for various propagation directions and polarizations
  • Compare results of test sim to old implementation
  • resolve possible issues
• DispersivePulse:
  • Compile test simulation for various propagation directions and dispersion values
  • Compare results of test sim to old implementation
  • resolve possible issues

Close #5269

[steindev]

@psychocoderHPC @PrometheusPi @chillenzer @ikbuibui PR is ready for review now.

It is intentionally split in three commits each of which refactors a specific part of the old implementation.

Test results have been discussed offline already and are documented in #5269.
Main takeaway from the tests: Results are equal between old and refactored implementation in various cases. Additionally, stray fields are reduced in the new implementation.