[sBTC DR 0.2] add stx withdrawal requests

[friedger]

Summary of Changes

This PR adds the possibility to make withdrawal requests as Stacks transactions.

• Implemented updates of clarity contract
• Implemented updates of romeo engine

Fixes #250

Testing

Risks

This introduces new complexity for users and developers.
Users might mix up how they requested to withdraw.
Indexers might not track the requests correctly.

How were these changes tested?

For clarity, one unit test was added. More to come.

What future testing should occur?

More unit tests.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[codecov]

Codecov Report

Attention: 37 lines in your changes are missing coverage. Please review.

Comparison is base (79f2c17) 39.35% compared to head (cec899a) 39.16%.
Report is 30 commits behind head on main.

Files	Patch %	Lines
romeo/asset-contract/contracts/asset.clar	12.50%	34 Missing and 1 partial ⚠️
romeo/asset-contract/tests/asset_test.clar	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #253      +/-   ##
==========================================
- Coverage   39.35%   39.16%   -0.20%     
==========================================
  Files          45       45              
  Lines        5229     5273      +44     
  Branches       47       58      +11     
==========================================
+ Hits         2058     2065       +7     
- Misses       3170     3206      +36     
- Partials        1        2       +1     

Flag	Coverage Δ
unittests	67.46% <15.90%> (-9.15%)	⬇️

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[CLAassistant]

All committers have signed the CLA.