Move progress-bar.cc to libmain

Needed so that we can include it as a logger in loggers.cc without
adding a dependency on nix

This also requires moving names.hh to libutil to prevent a circular
dependency between libmain and libexpr

src/libutil/names.hh

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <memory>
+
+#include "types.hh"
+#include <regex>
+
+namespace nix {
+
+struct DrvName
+{
+    string fullName;
+    string name;
+    string version;
+    unsigned int hits;
+
+    DrvName();
+    DrvName(std::string_view s);
+    bool matches(DrvName & n);
+
+private:
+    std::unique_ptr<std::regex> regex;
+};
+
+typedef list<DrvName> DrvNames;
+
+string nextComponent(string::const_iterator & p,
+    const string::const_iterator end);
+int compareVersions(const string & v1, const string & v2);
+DrvNames drvNamesFromArgs(const Strings & opArgs);
+
+}