Validate command/config flags when exporting HTML table

[Robyt3]

Prevent new config/command flags from being added without also handling them in the HTML table export script.

Checklist

• Tested the change: no difference in output
• Provided screenshots if it is a visual change
• Tested in combination with possibly related configuration options: adding an unknown command flag (Reduce conditional compilation of debug dummies #11546)
• Written a unit test (especially base/) or added coverage to integration test
• Considered possible null pointers and out of bounds array indexing
• Changed no physics that affect existing maps
• Tested the change with ASan+UBSan or valgrind's memcheck (optional)
• I didn't use generative AI to generate more than single-line completions

[ChillerDragon]

I personally would split on "|" and then strip it. To not make this check dependent on the clang formatter. But eh whatever. That is basically one of the key benefits of using a formatter to not have to write flexible code parsers anymore. I just find it annoying when I get a failing CI and when trying to investigate the issue I realize it was actually another test that failed (formatting) which caused it.