Use index_map in distributed::matrix

[MarcelKoch]

Application of #1543. Now the index_map is used to create the numbering for the non-local columns. The index_map is created during the distributed::matrix::read_distributed and also returned from that function. This can allow users to provide already separated local and non-local matrices for the read_distributed further down the line. Also, it makes the mapping non-local -> global more easily available.

This PR also introduces:

• making run easier to use
• specialization of run for distributed matrices -> removes need for changes to distributed base

PR Stack:

• [ ] #1545
• [ ] #1543
• [ ] #1579
• [ ] #1544
• [ ] #1588
• [ ] #1589

[MarcelKoch]

There is some interface breaking stuff in there, but it's minor and I can easily add the old version, if necessary.

[sonarcloud[bot]]

Quality Gate passed

Issues
19 New issues
0 Accepted issues

Measures
0 Security Hotspots
92.3% Coverage on New Code
3.6% Duplication on New Code

See analysis details on SonarCloud