linalg: refactor blas/lapack modules

[jalvesz]

Major refactoring of the blas/lapack modules into submodules for improved build speed and potentially better organization of procedures. This PR follows #908

• The reference files and refactoring script are currently within the legacy folder which should be removed before merging.
• Two folders have been added: blas and lapack to organize all required files within.
• The splitting is managed by the legacy\refactor_blaslapack_subm.py script which contains 3 dictionaries: blas_groups, lapack_groups, lapack_subgroups. The first two list the procedures in groups following lapacks documentation with some extra arbitrary splitting in order to improve parallel build. Given that the use of submodules requires a header module to declare the procedures signature, putting all lapack procedures into a single header implies a stall in the build process while building this single header. The dictionary lapack_subgroups proposes to split into modules which define macro-groups for the submodules.