Redefine classes `Dot` and `Inner` to mimic FEniCSx for complex values

[tomcaruso]

• The Inner class should compute the inner scalar product of two arguments which may be scalars, vectors, or matrices. The result should always be scalar. It should also compute the complex or real inner product based on argument type.
• The antilinearity in the SesquilinearForm and in the Inner should be applied to the second argument (aka to the test function).
• Make sure that our norms return a real non-negative number.
• The Dot class should be redesigned to compute the contraction between the last index of the first argument and the first index of the second argument.
• Psydac: change name of VectorSpace.dot() into VectorSpace.inner()

[campospinto]

How is this related with PR #133 ?

[yguclu]

How is this related with PR #133 ?

The second point in the to-do list in the PR description mentions sesquilinear forms