Add custom rosdoc2 config for ros2_control metapackage (backport #1484)

[mergify]

rosdoc2 will be used by the build farm to publish API docs on http:https://docs.ros.org/en/rolling/p/ros2_control/ which is empty now.

• remove doxyfile because it is added to control.ros.org and used here API docs for the whole stack via doxygen control.ros.org#278
• Add custom landing page for rosdoc2: logo, links to control.ros.org
• add rosdoc2 workflow, but only if the relevant files changed

---

This is an automatic backport of pull request #1484 done by [Mergify](https://mergify.com).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.45%. Comparing base (ae2ed7c) to head (e8f236e).
Report is 3 commits behind head on iron.

Additional details and impacted files

@@           Coverage Diff           @@
##             iron    #1589   +/-   ##
=======================================
  Coverage   87.45%   87.45%           
=======================================
  Files         101      101           
  Lines        8078     8078           
  Branches      711      711           
=======================================
  Hits         7065     7065           
  Misses        717      717           
  Partials      296      296           

Flag	Coverage Δ
unittests	87.45% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.