feat(coax): add coaxial models

Squashed commit of the following:

commit dc1fc8f4
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Mon Sep 25 17:33:56 2023 +0200

    feat(coax): add sst and mst coax models + refact

    Complete refactoring of the updateupstreamvel function in order to
    facilitate inclusion of new models.

    Added Single StreamTube model and a more exact calculation of the
    streamtube constraction using the MST model.

commit 422dc457
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Fri Sep 22 14:53:42 2023 +0200

    feat(coax,WIP): add options for contraction

commit 8ad23625
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 15:07:12 2023 +0200

    fix(ElemPerf): issue with contraction

    The contraction should be calculated based on the **last element**
    position and not the actual rotor radius.

    In some edge cases, an element of the aft rotor can fall in between the
    contraction calculated from the previous rotor's last element and the one
    calculated from its tip radius. When this happens, the velocity is
    poorly interpolated and brought to 0 for this element on the aft rotor.
    This not only skews the results, but also lead to issues with the
    current implementation of the indfact solver, which only looks into
    Op.speed~=0 and into the airspeed for each individual elements.

commit ccf3cfb4
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 15:06:05 2023 +0200

    fix(solvers): use proper upstreamvel in all solvers (closes #12)

commit eeb8cc2f
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 13:13:20 2023 +0200

    fix(Result): display op pts for multi-rotors (closes #15)

commit c8525bcb
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 11:38:50 2023 +0200

    feat(solvers, WIP): coax for all solvers

commit 67225be0
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 10:59:46 2023 +0200

    refact(config): more generic coax template

commit bd6c21b5
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 10:56:18 2023 +0200

    refact(result): improve result tables

commit 4b24a542
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Wed Sep 20 09:48:46 2023 +0200

    chore(bemt): add warning for coax solvers

commit ab5bc9f7
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Tue Sep 19 16:50:30 2023 +0200

    doc(Blade): spindir definition

commit d639096e
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Tue Sep 19 16:46:31 2023 +0200

    chore(template): minor adjustments

commit 76f8791d
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Tue Sep 19 16:21:33 2023 +0200

    chore(valid): add checks for spindir and hubpos

commit 510808d0
Merge: 83427a00 af545953
Author: Thomas Lambert <t.lambert@uliege.be>
Date:   Tue Sep 19 14:08:07 2023 +0000

    Merge branch 'coax_LR_new' into 'dev_coax'

    feat: add SMST coaxial model
    See merge request rotare/rotare!6

commit af545953
Author: Rakotondratsimba Lyraie <liz_tp@proton.me>
Date:   Tue Sep 19 14:08:07 2023 +0000

    feat: add SMST coaxial model

    - Adapt upstream velocity definition
    - Proper calculation of inflow velocity for second rotor
    - Modify Results class to store multiple rotors
    - Adapt BEMT indvel