Fixes for composer

[prabhu]

None of the frontier models and I can answer the question about whether the version is mandatory or not for composer! I'm assuming it is mandatory. All the tests include version, so reinforces the view that the version is mandatory.

• Defined Requirements: The name_definition and version_definition are now correctly marked as "required", as they are mandatory components for a valid composer purl.
• Added Normalization Rules: To enforce the lowercasing requirement, normalization_rules have been added to both the namespace_definition and name_definition.
• Improved Descriptions: The note for the version_definition has been added to state clearly that the version is a required component.
• Expanded Examples: An additional example from the reference has been included to provide better coverage.