Enhance LinuxFsI2CBus validation with detailed exception messages and comprehensive Javadocs

[dariuszzbyrad]

This update improves the LinuxFsI2CBus class by addressing ambiguous exception messages and enhancing documentation:

• Detailed Exception Messages: Previously, all validation failures for sysfs and devfs paths (e.g., non-existence, unreadable, unwritable) shared the same error message. These are now split into specific messages, making it easier to diagnose the exact issue during initialization.
• Comprehensive Javadocs: Added or refined Javadoc comments for all methods and fields to provide clear explanations of their purpose, parameters, and behaviors.
• Code Refactoring: Streamlined validation methods (validateSysFs and validateAndGetDevFs) to improve readability and maintainability while preserving functionality.

[FDelporte]

Good idea for the extended error messages! We could probably use more of these through the code... ;-)
@taartspi @eitch OK to merge?

[eitch]

Looks good, thanks for the cleanup