Move Go models to Packages::Go

What does this MR do?

• Moves Packages::GoModule to Packages::Go::Module
• Moves Packages::GoModuleVersion to Packages::Go::ModuleVersion

These models were introduced in !27746 (merged). The models for the other package managers were refactored after work was begun on !27746 (merged) but before it was merged.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Style guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.