Replace ins trait

[lukhio]

We have a finite set on instructions format so there is no need for a trait. An enum works.

[codecov]

Codecov Report

Attention: 215 lines in your changes are missing coverage. Please review.

Comparison is base (97e1601) 90.57% compared to head (4abce6e) 80.24%.

Files	Patch %	Lines
src/disasm.rs	0.00%	189 Missing ⚠️
src/dex_classes.rs	0.00%	14 Missing ⚠️
src/code_item.rs	0.00%	11 Missing ⚠️
src/dex_file.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #14       +/-   ##
===========================================
- Coverage   90.57%   80.24%   -10.34%     
===========================================
  Files          22       22               
  Lines        6199     5410      -789     
===========================================
- Hits         5615     4341     -1274     
- Misses        584     1069      +485     

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