Gas accounting for fee unshielding

[grarco]

Describe your changes

Closes #2592.

Modifies the protocol logic to charge the gas consumed by the fee unshielding operation, which therefore will pay fees. The gas is charged to the GasLimit declared by the transaction.

Adds an integration test to verify that a fee unshielding operation can run out of gas.

Indicate on which release or other PRs this topic is based on

v0.33.0

Checklist before merging to draft

• [x] I have added a changelog
• [x] Git history is in acceptable state

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 19.81132% with 170 lines in your changes are missing coverage. Please review.

Project coverage is 59.37%. Comparing base (97ec5b4) to head (b57ec8b). Report is 4 commits behind head on main.

Files	Patch %	Lines
crates/namada/src/ledger/protocol/mod.rs	10.00%	90 Missing :warning:
crates/apps/src/lib/node/ledger/shell/mod.rs	15.18%	67 Missing :warning:
crates/gas/src/lib.rs	0.00%	13 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2619      +/-   ##
==========================================
- Coverage   59.39%   59.37%   -0.02%     
==========================================
  Files         298      298              
  Lines       92771    92785      +14     
==========================================
- Hits        55104    55095       -9     
- Misses      37667    37690      +23     

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