Add float helpers

[Schamper]

Closes #159

I couldn't really think of a good name for the float packer, so I just called it pf16, pf32 and pf64.

[codspeed-hq]

Merging this PR will not alter performance

✅ 14 untouched benchmarks

---

_{Comparing add-float-helpers (b9b2de9) with main (32253fe)}

[codecov]

Codecov Report

❌ Patch coverage is 0% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (32253fe) to head (b9b2de9).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/cstruct/util.py	0.00%	23 Missing ⚠️
dissect/cstruct/compiler.py	0.00%	1 Missing ⚠️
dissect/cstruct/types/base.py	0.00%	1 Missing ⚠️
dissect/cstruct/types/packed.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #167   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files         22      22           
  Lines       2785    2798   +13     
=====================================
- Misses      2785    2798   +13     

Flag	Coverage Δ
unittests	0.00% <0.00%> (ø)

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[Miauwkeru]

shouldn't these pf# and f# functions also be exposed in dissect/cstruct/__init__.py just like the p# and u# functions?

[Schamper]

@copilot add this and make sure linting passes

[Copilot]

Done — pf16, pf32, pf64, f16, f32, f64 are now exported from dissect/cstruct/__init__.py (both in the import block and __all__). Linting passes. Commit: Expose pf16, pf32, pf64, f16, f32, f64 in __init__.py.