[Multivec 5/5]: Parallel SpMV updates

[victorapm]

This is part of a series of PRs for enabling BoomerAMG to be applied to multivectors.

Changes in this PR:

1. Extend hypre_ParCSRCommPkg with a new member (num_components) that allows communicating several vector components at once.
2. Add hypre_ParCSRCommPkgCreateAndFill for allocating and filling a communication package with its data. This function makes it easier to propagate changes in the commPkg throughout hypre
3. Improve the performance of ParCSRMatrixMatVec and ParCSRMatrixMatvecT for multivectors. The idea is to pack vector components together when doing communication.

Note: other multivec branches have been merged into this one since some of the functionalities added here depend on the others.

Regression tests:

• [ ] Tux
• [ ] Lassen