feat: Add integration tests for token contract

[ritik4ever]

feat: Add Integration Tests for Token Contract

Closes #32

Description

This pull request introduces integration tests for the sanctifier-core analyzer to verify its ability to detect common vulnerabilities in Soroban token contracts.

To facilitate this, a new vulnerable contract, token-with-bugs, has been added. This contract includes the following intentional vulnerabilities:

• Missing Authorization: The transfer function can be called without a require_auth check, allowing unauthorized transfers.
• Integer Overflow: The mint and transfer functions perform arithmetic operations without using checked arithmetic, making them vulnerable to integer overflow/underflow attacks.

Changes

• Created a new contract contracts/token-with-bugs with the vulnerabilities described above.
• Added a new test case test_token_with_bugs to tooling/sanctifier-core/src/lib.rs.
• The new test uses the Analyzer to scan the token-with-bugs contract.
• Assertions have been added to confirm that scan_auth_gaps and scan_arithmetic_overflow correctly identify and report the vulnerabilities.

Testing

The changes were tested by running the sanctifier-core test suite. The new test test_token_with_bugs passes, confirming that the analyzer works as expected.

[ritik4ever]

@Gbangbolaoluwagbemiga please review my PR

[Gbangbolaoluwagbemiga]

@ritik4ever, please resolve conflicts