fix: BFloat16 extension and tests

[avik-pal]

the tests are still returning zero similar to #1695, but at least this tests if the extension loads correctly. Marked them as broken for now.

fixes #1723

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 68.30%. Comparing base (02c5855) to head (48e4f0c).

Files	Patch %	Lines
ext/EnzymeBFloat16sExt.jl	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1725      +/-   ##
==========================================
+ Coverage   67.39%   68.30%   +0.90%     
==========================================
  Files          32       41       +9     
  Lines       12772    13183     +411     
==========================================
+ Hits         8608     9004     +396     
- Misses       4164     4179      +15     

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[ChrisRackauckas]

I'm getting reports about this causing lots of test and tutorial failures. Is the patch being released?