Refactor Gas type

[grarco]

Describe your changes

Closes #3555.

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes

[codecov]

Codecov Report

Attention: Patch coverage is 92.54766% with 43 lines in your changes missing coverage. Please review.

Project coverage is 72.70%. Comparing base (ff2f43c) to head (ce149f9).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/vm/src/host_env.rs	84.50%	11 Missing ⚠️
crates/state/src/lib.rs	77.14%	8 Missing ⚠️
crates/vp/src/vp_host_fns.rs	27.27%	8 Missing ⚠️
crates/ibc/src/vp/context.rs	54.54%	5 Missing ⚠️
crates/shielded_token/src/validation.rs	87.50%	5 Missing ⚠️
crates/state/src/wl_state.rs	83.33%	2 Missing ⚠️
crates/vp_prelude/src/lib.rs	0.00%	2 Missing ⚠️
crates/node/src/storage/rocksdb.rs	85.71%	1 Missing ⚠️
crates/storage/src/mockdb.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3792      +/-   ##
==========================================
+ Coverage   72.67%   72.70%   +0.02%     
==========================================
  Files         338      338              
  Lines      104340   104467     +127     
==========================================
+ Hits        75827    75948     +121     
- Misses      28513    28519       +6     

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