Fix color mode, favicon, and switch out youtube embed to use nextjs builtin lib

[thostetler]

• flip around the favicon directories light<->dark
  • Now the light directory has the "light" icons and vice versa
• fix favicon color scheme issue
• fix color mode issue
• Change the youtube embed to use nextjs builtin

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 45 lines in your changes are missing coverage. Please review.

Project coverage is 47.6%. Comparing base (5613fb6) to head (114be0f).

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #447     +/-   ##
========================================
- Coverage    47.6%   47.6%   -0.0%     
========================================
  Files         405     405             
  Lines       41496   41518     +22     
  Branches      593     594      +1     
========================================
- Hits        19741   19737      -4     
- Misses      21741   21767     +26     
  Partials       14      14             

Files	Coverage Δ
src/ssr-utils.ts	39.8% <0.0%> (ø)
src/components/Favicons/Favicons.tsx	2.0% <0.0%> (-8.3%)	⬇️

... and 1 file with indirect coverage changes