[lldb][Module] Only log SDK search error once per debugger session (llvm#171820)

Currently if we are debugging an app that was compiled against an SDK
that we don't know about on the host, then every time we evaluate an
expression we get following spam on the console:
```
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
error: Error while searching for Xcode SDK: Unrecognized SDK type: <some SDK>
```

It is not a fatal error but the way we spam it pretty much ruins the
debugging experience.

This patch makes it so we only log this error once per debugger session.

Not sure how to best test it since we'd need to build a program with a
particular SDK and then make it unrecognized by LLDB. Confirmed manually
that the error only gets reported once after this patch.

(cherry picked from commit 1b7f272)

Author: Michael137

lldb/source/Core/Module.cpp

@@ -1706,7 +1706,9 @@ void Module::RegisterXcodeSDK(llvm::StringRef sdk_name,
 
   if (!sdk_path_or_err) {
     Debugger::ReportError("Error while searching for Xcode SDK: " +
-                          toString(sdk_path_or_err.takeError()));
+                              toString(sdk_path_or_err.takeError()),
+                          /*debugger_id=*/std::nullopt,
+                          GetDiagnosticOnceFlag(sdk_name));
     return;
   }