Standardizing dialog button boxes across material editor and component

Making dialogs modal

https://jira.agscollab.com/browse/ATOM-15173

https://jira.agscollab.com/browse/ATOM-15174

Gems/Atom/Tools/MaterialEditor/Code/Source/Window/CreateMaterialDialog/CreateMaterialDialog.cpp

@@ -37,6 +37,8 @@ namespace MaterialEditor
         //Connect ok and cancel buttons
         QObject::connect(m_ui->m_buttonBox, &QDialogButtonBox::accepted, this, &QDialog::accept);
         QObject::connect(m_ui->m_buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);
+
+        setModal(true);
     }
 
     void CreateMaterialDialog::InitMaterialTypeSelection()

Gems/Atom/Tools/MaterialEditor/Code/Source/Window/PresetBrowserDialogs/PresetBrowserDialog.cpp

@@ -35,6 +35,7 @@ namespace MaterialEditor
         SetupPresetList();
         SetupSearchWidget();
         SetupDialogButtons();
+        setModal(true);
     }
 
     void PresetBrowserDialog::SetupPresetList()