Remove BigFloat from conversions and decompose for small DoubleFloats

[oscardssmith]

to hopefully make them more gpu compatible

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 49.68%. Comparing base (bdf1855) to head (6aaa42a).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Double.jl	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #215      +/-   ##
==========================================
- Coverage   50.56%   49.68%   -0.89%     
==========================================
  Files          63       63              
  Lines        3536     3446      -90     
==========================================
- Hits         1788     1712      -76     
+ Misses       1748     1734      -14     

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[JeffreySarnoff]

groovy thanks