Make blade parameters consistent

[RobinKa]

Right now when passing blades to functions, we either pass blade indices, blade kind or blade names. This should be made more consistent so all functions take the same type of input.

Two possible options:

• Make everything take blade indices, provide functions to easily convert from kind or name to index
• Create a new data structure that can hold one of the three and make all functions accept this data structure

[RobinKa]

Made select_blades and keep_blades take blade indices instead of names in https://github.com/RobinKa/tfga/commit/26ecef36ae0941b12319e312baffb75c2035dadf and added functions taking names select_blades_with_name and keep_blades_with_name with the old behavior.