[Core] Explicit x and v vectors in addForce

[alxbilger]

Allow to define the x vector as an input of addForce, instead of implicitly relying on the x vector from mparams.

Similar to #6281 and #6288

[ci-depends-on https://github.com/SofaDefrost/Cosserat/pull/187]

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Reviewers will merge this pull-request only if

• it builds with SUCCESS for all platforms on the CI.
• it does not generate new warnings.
• it does not generate new unit test failures.
• it does not generate new scene test failures.
• it does not break API compatibility.
• it is more than 1 week old (or has fast-merge label).

[alxbilger]

[ci-build][with-all-tests]

[sofabot]

[ci-depends-on] detected during build #3.

To unlock the merge button, you must

• Merge or close adapt to #6291 (addForce) SofaDefrost/Cosserat#187
  For this build, the following CMake flags will be set
  -DCOSSERAT_GIT_REPOSITORY='https://github.com/SofaDefrost/Cosserat'
  -DCOSSERAT_GIT_TAG='71128243b4333e3685f67feeae7d9f1507dcf728'

[sofabot]

[ci-depends-on] detected during build #4.

To unlock the merge button, you must

• Merge or close adapt to #6291 (addForce) SofaDefrost/Cosserat#187
  For this build, the following CMake flags will be set
  -DCOSSERAT_GIT_REPOSITORY='https://github.com/SofaDefrost/Cosserat'
  -DCOSSERAT_GIT_TAG='71128243b4333e3685f67feeae7d9f1507dcf728'

[hugtalbot]

Same here (conflicts) @alxbilger