Utils: Rename most FilePath::{from,to}Variant uses to {from,to}Settings

Specifies the main purpose more clearly. The remaining ones a "true"
(internal) variants in models and as action data.

Change-Id: I8dd3c846e419f29d88283c2f48268ef6685b19fe
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/vcsbase/vcsbaseclient.cpp

@@ -309,7 +309,7 @@ bool VcsBaseClient::synchronousPull(const FilePath &workingDir,
     const bool ok = vcsSynchronousExec(workingDir, args, flags).result()
             == ProcessResult::FinishedWithSuccess;
     if (ok)
-        emit changed(workingDir.toString());
+        emit changed(workingDir.toVariant());
     return ok;
 }