Refactor execute_dynamic with Execution struct

[louisfd]

Quick refactor regarding JIT kernels

[antimora]

LGTM

[codecov]

Codecov Report

Attention: Patch coverage is 99.22179% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 86.31%. Comparing base (279be04) to head (cd5e07a).
Report is 2 commits behind head on main.

Files	Patch %	Lines
backend-comparison/src/burnbenchapp/base.rs	0.00%	1 Missing ⚠️
crates/burn-jit/src/codegen/kernel.rs	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1550      +/-   ##
==========================================
- Coverage   86.36%   86.31%   -0.05%     
==========================================
  Files         683      683              
  Lines       78200    78091     -109     
==========================================
- Hits        67535    67408     -127     
- Misses      10665    10683      +18     

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