Upgrade tgfx to b8251c0 and adapt new vertex buffer API.

[richardshan0614]

• Upgrade tgfx dependency to b8251c0
• Adapt to new VertexBufferLayout API (replacing VertexDescriptor)
• Fix RenderPass::draw() call to match new API signature

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.20%. Comparing base (ea3d023) to head (33aa8c7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3223      +/-   ##
==========================================
- Coverage   77.21%   77.20%   -0.01%     
==========================================
  Files         413      413              
  Lines       21910    21911       +1     
  Branches     6291     6292       +1     
==========================================
- Hits        16918    16917       -1     
- Misses       3802     3805       +3     
+ Partials     1190     1189       -1     

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