chore: Remove unused iexec NPM packages @iexec/interface and @iexec/solidity

[zguesmi]

Replace #310

[Copilot]

Pull Request Overview

This PR removes external dependencies @iexec/interface and @iexec/solidity from the project, consolidating the codebase to use locally implemented contracts instead. The changes reduce external dependencies and simplify imports.

• Removed @iexec/interface and @iexec/solidity npm packages
• Consolidated InitializableUpgradeabilityProxy__factory import to use the main typechain export
• Updated Solidity compiler version comments for clarity

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
test/byContract/registries/registries.test.ts	Simplified import by removing the separate import for InitializableUpgradeabilityProxy__factory and using the main typechain export
package.json	Removed @iexec/interface and @iexec/solidity dependencies along with related TODO comment
package-lock.json	Cleaned up entries for removed dependencies and their transitive dependencies
hardhat.config.ts	Updated comments to reflect that 0.8.21 is used for PoCo contracts and 0.6.12 is for external dependencies

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[Le-Caignec]

LGTM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.32%. Comparing base (7f2865f) to head (03c8988).
⚠️ Report is 1 commits behind head on chore/solidity-v8.

Additional details and impacted files

@@                Coverage Diff                 @@
##           chore/solidity-v8     #319   +/-   ##
==================================================
  Coverage              96.32%   96.32%           
==================================================
  Files                     34       34           
  Lines                   1117     1117           
  Branches                 223      223           
==================================================
  Hits                    1076     1076           
  Misses                    41       41           

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