Make the si4ti C++ library available in Python

[dafeda]

Similar in scope to this issue:

equinor/seismic-forward#85

TODO

Needs API design

[anders-kiaer]

How simpli is used today in fmu-sim2seis:

• https://github.com/equinor/fmu-sim2seis/blob/91a149bdc365edf7c6e374f9c31235f388acc7de/src/fmu/sim2seis/seismic_inversion/__main__.py#L43-L50

• https://github.com/equinor/fmu-sim2seis/blob/91a149bdc365edf7c6e374f9c31235f388acc7de/src/fmu/sim2seis/seismic_inversion/simpli_4d_inversion.py#L31-L166