Issue Description: Tiles under overhangs dont render if the blocks underneath arent lit

• Dynmap Version: 3.4 Beta-3-774
• Server Version: Paper Build 317 for 1.18.2
• Server Host (if applicable): Selfhosted
• Other Relevant Data/Screenshots: See below
• Steps to Replicate: Have Overhang in world, have it be unlit, see problem.

[x] I have looked at all other issues and this is not a duplicate
[x] I have been able to replicate this

Custom Perspective:

perspectives:
  - class: org.dynmap.hdmap.IsoHDPerspective 
    name: iso_idunno_SE_60_i_guess_very_hires
    azimuth: 135
    inclination: 60
    scale: 32

Screenshots:

Chunks that have not been lit by the server itself (which happens when the server has not completely upgraded the chunks from a previous version to a new version) will have issues like this: we have a simple lighting system so that the chunks don't wind up being black (due to having discarded their lighting data - a thrilling and asinine behavior that the vanilla code started doing back around 1.17), but we are NOT regenerating a full lighting system. This is a permanent limitation - if you drive the chunks to be fully migrated by visiting the chunks in-game, or using some other mod that drives such migration to completion, the rendering will work as expected.