refactor(apt): changes to validation and test cases

[shivam-bitgo]

Ticket: COIN-5352

This pull request refactors and centralizes validation logic for Aptos custom transaction module and function names, ensuring stricter compliance with expected formats (hex addresses only for module names). It also updates usage throughout the codebase to leverage the new validation utilities, improves test coverage for valid and invalid cases, and adds new tests for custom token mint and burn transactions.

Validation logic refactor and enforcement:

• Introduced new validation utilities in utils/validation.ts for module and function names, providing both throwing (validateModuleName, validateFunctionName) and non-throwing (isValidModuleName, isValidFunctionName) variants. These utilities enforce module names to use only hex addresses and valid function identifiers.
• Removed inline regex validation methods from CustomTransaction and replaced their usage with calls to the centralized validation utilities.

Transaction builder validation updates:

• Updated CustomTransactionBuilder to use the new validation utilities for checking module and function name formats, removing previous regex and address checks.

Testing improvements:

• Modified unit tests to reject named addresses for module names, ensuring only hex addresses are accepted, and updated error expectations accordingly.
• Added new tests for building custom token mint and burn transactions at deployed hex addresses, verifying correct construction and validation of these transaction types.

[shivam-bitgo]

rebased as there were merge conflicts

[sampras-saha]

LGTM