Update disposable signer

[grarco]

Describe your changes

Closes #3424.

Removes the disposable-gas-payer arg from the general Tx args and makes it specific to a set of transactions:

• TxShieldedTransfer
• TxUnshieldingTransfer
• TxIbc
• TxCustom
• The SignTx struct used to sign transactions offline

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 0% with 46 lines in your changes missing coverage. Please review.

Project coverage is 61.16%. Comparing base (2256e38) to head (86f053e).
Report is 7 commits behind head on main.

Files	Patch %	Lines
crates/sdk/src/tx.rs	0.00%	29 Missing ⚠️
crates/sdk/src/lib.rs	0.00%	7 Missing ⚠️
crates/sdk/src/args.rs	0.00%	6 Missing ⚠️
crates/sdk/src/eth_bridge/bridge_pool.rs	0.00%	2 Missing ⚠️
crates/sdk/src/signing.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3699      +/-   ##
==========================================
- Coverage   61.17%   61.16%   -0.02%     
==========================================
  Files         315      315              
  Lines      103187   103220      +33     
==========================================
+ Hits        63129    63131       +2     
- Misses      40058    40089      +31     

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[brentstone]

Fixed some spelling, otherwise LGTM!