Feature/base spatialparams v2

An alternative approach to !2839 (closed).

TODO:

• add new versions for geomechanics params
• add new version for nonequilibrium params
• port the tests, which requires moving temperature and extrusionFactor into the spatial params (dumux day task?)

TODOS for follow-up merge requests (!!!Before merging this we should open respective issues!!!):

• use spatial params in free flow models (-> Fixes #1111 (closed))
• move porenetwork spatial params in pore-network folder? (-> Fixes #1112 (closed))
• move fluid property interfaces from geomechanics problem into geomech spatial params and deprecate problem (-> Fixes #1113 (closed))

Test folder ports:

• 1p (@IvBu) !2906 (merged)
• 1pnc (@RoWin) !2974 (merged)
• 1pncmin (@mathis) !2942 (merged)
• richards (@bernd) !2945 (merged)
• 2p (@stefaniekiemle) !2950 (merged)
• 2p1c (@mathis) !2943 (merged)
• mpnc (@DennisGlaeser) !2949 (merged)
• 2p2c (@mathis) !2955 (merged)
• 3p (@bernd) !2946 (merged)
• 3p3c (@bernd) !2947 (merged) which is based on !2946 (merged)
• richardsnc (@bernd) !2948 (merged) which is based on !2945 (merged)
• co2 (@bernd) !2957 (merged) which is based on !2955 (merged)
• tracer (@bernd) !2952 (merged) which is based on !2950 (merged)
• solidenergy (@DennisGlaeser) !2951 (merged)
• 2pnc (@mathis) !2956 (merged)
• multidomain (@DennisGlaeser) !2960 (merged)
• examples !2978 (merged)
• 2pncmin (@DennisGlaeser) (done here directly)