Support for Cross Account Builds

[dendilaws]

Description

Brief description of changes
Support for Cross Account Builds. Now supports CodeBuild in one account and AgentCore deployment in another account. Use the parameter "code_build_execution_role" to specify the codebuild role (example: "code_build_execution_role=arn:aws:iam::ACCOUNTB:role/CodeBuildCrossAccountRole", codebuild will happen in the account ACCOUNTB while the AgentCore deployment can be in another account)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• [x ] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring

Testing

• [ x] Unit tests pass locally
• [x ] Integration tests pass (if applicable)
• [x ] Test coverage remains above 80%
• [x ] Manual testing completed

Checklist

• [ x] My code follows the project's style guidelines (ruff/pre-commit)
• [ x] I have performed a self-review of my own code
• [ x] I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• [x ] My changes generate no new warnings
• [ x] I have added tests that prove my fix is effective or that my feature works
• [x ] New and existing unit tests pass locally with my changes
• [x ] Any dependent changes have been merged and published

Security Checklist

• [x ] No hardcoded secrets or credentials
• [x ] No new security warnings from bandit
• Dependencies are from trusted sources
• [x ] No sensitive data logged

Breaking Changes

List any breaking changes and migration instructions:

N/A

Additional Notes

Add any additional notes or context about the PR here.