Feature/default discretization local operator

See merge request !3977

[properties][cleanup] Remove property LinearSolver

See merge request !3984

[properties] Remove property DefaultModelParameters

See merge request !3975

[cmake] Propagate DUMUX_MULTITHREADING_BACKEND downstream

See merge request !3983

Feature/dep5 to reuse toml

Closes #1386

See merge request !3976

Update mailmap for Timo Koch

See merge request !3979

[cmake] Set DUMUX_MULTITHREADING_BACKEND in config.h

See merge request !3980

and only set it if it's not defined. We want to be able
to overwrite the flag per target (as for example used
for the Python bindings which enforce Serial)

Feature/pass localresidual to assembler

See merge request !3978

Fix freeflow couplingmanager issue

Closes #1419

See merge request !3972

The singleton approach fail as soon as one has two instances
of a coupling manager in the same program. The occurring error
is very hard to debug. Since the singleton failed to make the
coupling manager thread safe, we go back to mutable caches.

Note that theoretically we could work with locks but this
has been tested to introduce large overhead. Global caches
will need to be eliminated eventually. In the meantime, we
at least make it work for multiple couplingmanager instances.

Extending the coupling conditions between ff and pnm to include energy and compositional coupling conditions

See merge request !3659

remove transient test case as included in non-isothermal one, update reference files

[pm] fix static assert with template and AlwaysFalse

Closes #1430

See merge request !3969

and include when function should be deleted (after release 3.10)

[io] Make sure VtkOutputModule does not write fields with the same name

Closes #1391

See merge request !3968

[license] replace SPDX-FileCopyrightInfo with SPDX-FileCopyrightText

Closes #1369

See merge request !3964

[bin][util] remove targetfolder  in install script writer

Closes #1432

See merge request !3963

[ifsolver] Check if reconstruction is necessary

See merge request !3956