[refactor](fe) Upgrade remote storage FileSystem to SPI (Phase 1)

[morningman]

What problem does this PR solve?

Problem Summary:
Phase 1 of the Doris FE remote storage access layer refactoring. This consolidates the fs modules into a modern, unified, SPI-based architecture (inspired by Trino FileSystem).

Key changes:

1. Introduced Location as a strongly-typed URI value object.
2. Introduced FileEntry representing zero-Hadoop file metadata.
3. Introduced FileIterator for lazy iteration to prevent OOM on large directories.
4. Cleaned up FileSystem interface (IOException-based, Location-typed) and retained the old LegacyFileSystem (Status-based) for backward compatibility during migration.
5. Added LegacyFileSystemAdapter to bridge old and new interfaces.
6. Upgraded DorisInputFile and DorisOutputFile with location().
7. Created MemoryFileSystem for comprehensive unit testing without real storage.
8. Marked RemoteFile and ParsedPath as @deprecated with bidirectional converters.
9. Migrated Iceberg's DelegateFileIO to natively use the new FileSystem and Location API.

Release note

None

Check List (For Author)

• Test:
  • Unit Test (Added comprehensive tests for Location, FileEntry, and MemoryFileSystem. Passed all 39 new tests)
• Behavior changed: No
• Does this need documentation: No

[Thearas]

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1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
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4. Which code was refactored and why was this part of the code refactored?
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