Show correct structure_level on list_of_speakers projections

[luisa-beerboom]

This concerns the following projection types: list_of_speakers and current_list_of_speakers

The speakers currently listed in those projections are always represented with all of their structure levels listed, which is correct IF list_of_speakers_default_structure_level_time is 0.

If list_of_speakers_default_structure_level_time is bigger than 0, the following should happen:

• If the speaker doesn't have a structure_level_list_of_speakers_id, no structure level should be shown.
• If the speaker has a structure_level_list_of_speakers_id, only the structure level of that structure_level_list_of_speakers should be shown

[ostcar]

@luisa-beerboom Is this still needed? What is the priority?

[luisa-beerboom]

This is definitely still needed.
As for the priority, @Elblinator and @rrenkert would be better judges of that.