feat: remove hardhat-dependency-compiler from contracts/test

Remove hardhat-dependency-compiler plugin as it's no longer needed.

The hardhat-dependency-compiler plugin was a historical workaround
that is no longer necessary for the current codebase structure.

Changes:
- Remove hardhat-dependency-compiler import and configuration from
  packages/contracts/test/hardhat.config.ts
- Remove getContractPaths() and findSolidityFiles() helper functions
- Remove hardhat-dependency-compiler dependency from
  packages/contracts/test/package.json
- Clean up hardhat-dependency-compiler directory reference from
  packages/contracts/package.json clean script
- Clean up unused imports (fs)

Author: RembrandtK

packages/contracts/package.json

@@ -35,7 +35,7 @@
   ],
   "scripts": {
     "prepack": "pnpm build",
-    "clean": "rm -rf artifacts/ cache/ types/ abis/ build/ dist/ contracts/hardhat-dependency-compiler/",
+    "clean": "rm -rf artifacts/ cache/ types/ abis/ build/ dist/",
     "build": "pnpm build:self",
     "build:self": "pnpm compile",
     "compile": "hardhat compile",