feat(tools/spxls): implement diagnostic features and improve VFS

[aofei]

Updates #1059

[qiniu-prow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[aofei]

这个文件可以不用看

Copilot reviewed 8 out of 20 changed files in this pull request and generated no suggestions.

Files not reviewed (12)

• tools/spxls/go.mod: Language not supported
• tools/spxls/internal/pkgdata/.gitignore: Language not supported
• tools/spxls/internal/vfs/mapfs.go: Evaluated as low risk
• tools/spxls/internal/server/server.go: Evaluated as low risk
• tools/spxls/internal/server/utils.go: Evaluated as low risk
• tools/spxls/internal/vfs/gopparserfs.go: Evaluated as low risk
• tools/spxls/main.go: Evaluated as low risk
• tools/spxls/internal/server/format_test.go: Evaluated as low risk
• tools/spxls/internal/server/format.go: Evaluated as low risk
• tools/spxls/README.md: Evaluated as low risk
• tools/spxls/internal/server/diagnostic.go: Evaluated as low risk
• tools/spxls/internal/vfs/mapfs_test.go: Evaluated as low risk

[qiniu-ci]

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