Add support for normal and horizon maps in planetary HiPS

[10110111]

Description

This automatically adds the normal and horizon map surveys for a planet to the corresponding planet object, and these map surveys are passed to the albedo survey.

One limitation that I don't think is worth the trouble lifting is that if a normal or horizon map is present but has hips_order smaller than that of the albedo survey, the total order of the HiPS is reduced to the smallest of them. Particularly, with our data.stellarium.org/surveys/moon-normal this yields max order 2 instead of 3.

In the future I'm planning to add my versions of the Moon surveys, including all the items: albedo, normals, horizons, which will yield a better version of the current static Moon.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update
• Housekeeping

How Has This Been Tested?

Test Configuration:

• Operating system: Ubuntu 20.04
• Graphics Card: Intel UHD Graphics 620

Checklist:

• My code follows the code style of this project.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (header file)
• I have updated the respective chapter in the Stellarium User Guide
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching src/**/*.cpp:

• Are possibly unused includes removed?

This is an automatically generated QA checklist based on modified files.

[gzotti]

This view becomes addictive :-)

[github-actions]

Hello @10110111!

Please check the fresh version (development snapshot) of Stellarium:
https://github.com/Stellarium/stellarium-data/releases/tag/weekly-snapshot

[github-actions]

Hello @10110111!

Please check the latest stable version of Stellarium:
https://github.com/Stellarium/stellarium/releases/latest