container: root: common: allow quotations in Pluggable arguments

Helps facilitate CLI usage; e.g.,

$ dfi testprofile/testuser root plugins/repo/bitcoin/bitcoin.cc 'dfi::macro::load(\"repo/test/unit.C\")'

container/src/root/common/utility.hh

@@ -26,8 +26,10 @@
 #include <ctime>
 #include <filesystem>
 #include <initializer_list>
+#include <iomanip>
 #include <iostream>
 #include <memory>
+#include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
@@ -619,11 +621,17 @@ class Pluggable
     // Load pluggable file
     ::dfi::common::load(m_plug.path().absolute());
 
-    // Execute pluggable's loader
-    const std::string s{
+    // Prepare pluggable entry
+    const std::string entry{
         "dfi::" + m_plug.space().outer() + "::" + m_plug.space().inner()
         + "::" + m_plug.space().entry()};
-    ::dfi::common::line(s + "::load(\"" + m_plug.args().load() + "\")");
+
+    // Allow quotations in loader argument
+    std::stringstream arg;
+    arg << std::quoted(m_plug.args().load());
+
+    // Execute pluggable's loader
+    ::dfi::common::line(entry + "::load(" + arg.str() + ")");
 
     return *this;
   }
@@ -634,11 +642,17 @@ class Pluggable
   //! \since docker-finance 1.1.0
   const auto& unload() const
   {
-    // Execute pluggable's unloader
-    const std::string s{
+    // Prepare pluggable entry
+    const std::string entry{
         "dfi::" + m_plug.space().outer() + "::" + m_plug.space().inner()
         + "::" + m_plug.space().entry()};
-    ::dfi::common::line(s + "::unload(\"" + m_plug.args().unload() + "\")");
+
+    // Allow quotations in unloader argument
+    std::stringstream arg;
+    arg << std::quoted(m_plug.args().unload());
+
+    // Execute pluggable's unloader
+    ::dfi::common::line(entry + "::unload(" + arg.str() + ")");
 
     // Unload pluggable file
     ::dfi::common::unload(m_plug.path().absolute());