go-llvm: expose exact source-location APIs

[zhouguangyuan0718]

Summary

• map DW_LANG_Go through the LLVM C API enum instead of using the raw DWARF encoding
• expose compile-unit emission kinds so Go can request line-tables-only metadata
• expose exact DILocation creation and builder get, set, and clear operations needed to preserve inlined-at chains without location leakage
• add binding tests for Go language metadata, line-tables-only emission, and exact debug-location state

Scope

These are the minimal bindings required to feed pcfile, pcline, and pcinline generation. This PR does not add type, variable, dbg.declare, or target-object DWARF APIs.

Validation

• GOENV=off go test -tags="llvm23 dynamicllvm" ./...

Related

• GoObj pcdata consumer: GoObj: emit pcfile, pcline, and pcinline from debug locations llvm-project#62
• the dependent Go compiler PR follows separately