Fix RestAPIClient decimal parsing in non-invariant cultures

[claudiamurialdo]

Improved GXRestAPIClient with optimized numeric handling and invariant culture support

• Added centralized GetBodyValue method to extract values directly from response data
• Optimized numeric parsing to avoid unnecessary string conversions when working with various numeric types
• Added trace error handling

Unit Tests:

• Added unit tests to verify invariant culture handling with decimal values
• Included culture-specific tests that verify correct behavior when system is using non-invariant cultures

Issue:204865

[genexusbot]

Cherry pick to beta success

• f33c2b8