Support Legacy and Jakarta-Prefixed Resource Files in JAF API with Legacy Precedence

Currently, the JAF API (MailcapCommandMap and MimetypesFileTypeMap) has been updated to support Jakarta-prefixed resources (e.g., jakarta.mailcap, jakarta.mime.types). However, to maintain backward compatibility, legacy resource files (mailcap, mime.types) also need to be loaded, with legacy files taking precedence when both forms are present.

This behavior aligns with the approach taken in Jakarta Mail 2.2.0 for provider and address map files, where both legacy (javamail.*) and Jakarta-prefixed resources are supported, but legacy entries have priority.

See https://github.com/jakartaee/mail-api/issues/812

Start with the resource-loading paths in MailcapCommandMap and MimetypesFileTypeMap. Compare their handling of Jakarta-prefixed resources with the legacy mailcap and mime.types names, using Jakarta Mail 2.2.0 and issue 812 as context. Done means both resource forms are supported and legacy entries take precedence when both are present.

Written by the indexing model from the issue text.