Fix binary response handling with regex conditions

[manofearth]

When using regex conditions (for URL or body) with binary response body, the content was incorrectly returned as a string with 'phiremock.base64:' prefix instead of actual binary data.

This PR fixes the issue by:

• Adding a check for BinaryBody instance in RegexResponseStrategy
• Bypassing regex replacement logic for binary responses since substitutions from regex capture groups are not applicable for binary data
• Adding a test case to verify binary response works correctly with regex URL matching

The change ensures binary responses (like images) are properly handled regardless of whether regex conditions are used in the expectation.

[mcustiel]

Nice catch. And thank you for taking care and covering it with tests ❤️