[Feature]: Add error handling around parse / load

[samatstariongroup]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of the EcoreNetto
• I have searched open and closed issues to ensure it has not already been reported

Description

• Summary: ECoreParser.ParseXml and Resource.Load perform file I/O and XML parsing with no try/catch, so missing files and malformed XML bubble up as raw framework exceptions with no context.
• Affected files: ECoreNetto/ECoreParser.cs:78-103, ECoreNetto/Resource/Resource.cs:308-321
• Proposed solution: Wrap I/O and XML loading, log with context, and either rethrow a domain-specific exception or record a diagnostic (B3). Ensure the documented FileNotFoundException behavior is actually produced.
• Acceptance criteria:
  • Missing-file and malformed-XML inputs produce a clear, documented error.
  • Tests cover both cases.