IWYU: phase 1

[hexagonrecursion]

• Ref Should we use include-what-you-use? #1796
• Ref missing includes #1437
• Ref Cannot build because of not included header for std::transform and std::sort #1776

My plan to add IWYU consists of three phases:

1. phase 1 - in this pull request I submit the changes needed before we can apply IWYU to the code. The github action will be disabled at this point because the #includes are not yet as IWYU wants them to be
2. phase 2 - after phase 1 is merged I will submit the automatically generated #include changes. hexagonrecursion@2cca382
3. phase 3 - after phase 2 is merged I will submit the third pull request to enable the github action hexagonrecursion@bd5aa7e