Overload functions l2Norm and lpNorm for 1D StaticVector
For 1D vectors, the `l2Norm` and `lpNorm` functions are equivalent to taking the absolute value of the 0-th component, so there should be overloads avoiding the expensive calls to `TNL::sqrt` and `TNL::pow`.
Then remove `getVectorLength` from [getEntityMeasure.h](https://mmg-gitlab.fjfi.cvut.cz/gitlab/tnl/tnl-dev/-/blob/develop/src/TNL/Meshes/Geometry/getEntityMeasure.h#L53-68).
issue