[lldb][test] Add test for completing ObjCObjectType (#95405)

This is a minimal reproducer for a crash where we would try to call
`DumpTypeDescription` on an incomplete type. This crash surfaced as

[lldb][test] Add test for completing ObjCObjectType (#95405)

This is a minimal reproducer for a crash where we would try to call
`DumpTypeDescription` on an incomplete type. This crash surfaced as part
of an NFC refactor of some of the logic in `GetCompleteQualType`:
```
(lldb) expr -l objc -- *(id)0x1234
Stack dump:
0. Program arguments: ./bin/lldb a.out -o "b main" -o run -o "expr -l objc -- *(id)0x1234"
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var LLVM_SYMBOLIZER_PATH to point to it):
0 lldb 0x0000000102ec768c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1 lldb 0x0000000102ec6010 llvm::sys::RunSignalHandlers() + 112
2 lldb 0x0000000102ec7fa8 SignalHandler(int) + 292
3 libsystem_platform.dylib 0x000000018c7a8c44 _sigtramp + 56
4 LLDB 0x0000000116b2030c lldb_private::TypeSystemClang::DumpTypeDescription(void*, lldb_private::Stream&, lldb::DescriptionLevel, lldb_private::ExecutionContextScope*) + 588
5 LLDB 0x00000001166b5124 lldb_private::CompilerType::DumpTypeDescription(lldb_private::Stream*, lldb::DescriptionLevel, lldb_private::ExecutionContextScope*) const + 228
6 LLDB 0x0000000116d4f08c IRForTarget::CreateResultVariable(llvm::Function&) + 2076
```

rdar://129633122

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