feat(data): implement time types support with pattern validation

[pinglin]

Because

• The data unmarshaling framework lacked native support for time.Duration and time.Time types, requiring manual string conversion in application code
• There was no pattern validation capability to enforce schema constraints during unmarshaling, leading to inconsistent data validation
• JSON number inputs could bypass intended string-only validation for duration fields, causing unexpected behavior
• Time types could not be marshaled back to consistent, API-compatible string formats
• The struct.go file contained significant code duplication that reduced maintainability

This commit

• Implements native time.Duration and time.Time unmarshaling: Automatically converts string values to Go time types with support for multiple parsing strategies including RFC3339, Go duration syntax, and custom seconds-based formats with pattern-based hints
• Adds comprehensive regex pattern validation: Validates string fields against patterns specified in instill tags using pattern= attribute, enabling enforcement of API schema constraints for any string field type
• Prevents JSON number bypass for time fields: Explicitly rejects JSON numbers for time.Duration fields, enforcing string-only input to maintain API contract compliance and prevent silent data corruption
• Enhances time type marshaling: Properly marshals time.Time as RFC3339 strings and time.Duration as Go duration strings for both pointer and non-pointer types
• Extends default value support: Handles default values for time types in struct tags with proper parsing validation using multiple time format attempts
• Optimizes code structure: Reduces code size by ~53 lines (4%) through extraction of helper functions, consolidation of duplicate logic, and streamlined parsing while maintaining 100% functionality
• Adds comprehensive test coverage: Includes extensive test suites for pattern validation scenarios, time type marshaling/unmarshaling, edge cases, and JSON number rejection

Key Features:

• Flexible duration parsing: Supports both standard Go duration format (1h30m) and seconds-based format (3600s, 3.5s) with pattern-based format detection
• Robust time parsing: Prioritizes RFC3339 for date-time format fields, with graceful fallback to multiple common time formats
• Generic pattern validation: Works with any string field type through regex pattern matching, enabling broad schema validation beyond time types
• Type safety: Prevents silent data corruption by explicitly rejecting incompatible input types (e.g., JSON numbers for duration fields)