Fixed find objects from search history

[alex-w]

Description

We're using custom objects to visualize locations of objects from SIMBAD (and when these objects are no exists in our database) currently and this feature in Search Tool works good for one session. In next session, these objects will be cannot found via search history - via SIMBAD only.

This pull request is enhancing the CustomObjectsMgr class via adding code for saving SIMBAD objects into special file and restoring list of saved files in next sessions.

Fixes #3199 (issue)

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?

1. Run Stellarium
2. Open Search Tool and find some objects via SIMBAD
3. Restart Stellarium
4. Open Search Tool and use list of latest founded objects

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.