inspector: Some ui refinements

Remove pointless expanders from lists, add grid lines and,
in some places, tree lines.

gtk/inspector/css-node-tree.ui

@@ -80,6 +80,7 @@
                 <property name="visible">1</property>
                 <property name="search-column">0</property>
                 <property name="enable-search">0</property>
+                <property name="enable-grid-lines">vertical</property>
                 <signal name="row-activated" handler="row_activated"/>
                 <signal name="button-press-event" handler="button_pressed"/>
                 <child internal-child="selection">

gtk/inspector/object-hierarchy.ui

@@ -27,6 +27,9 @@
             <property name="visible">True</property>
             <property name="model">model</property>
             <property name="enable-search">False</property>
+            <property name="enable-tree-lines">1</property>
+            <property name="show-expanders">0</property>
+            <property name="level-indentation">18</property>
             <child>
               <object class="GtkTreeViewColumn">
                 <property name="title" translatable="yes">Class Hierarchy</property>

gtk/inspector/object-tree.ui

@@ -82,6 +82,7 @@
             <property name="visible">True</property>
             <property name="model">model</property>
             <property name="enable-search">False</property>
+            <property name="enable-grid-lines">vertical</property>
             <signal name="row-activated" handler="on_row_activated"/>
             <child internal-child="selection">
               <object class="GtkTreeSelection">

gtk/inspector/prop-list.ui

@@ -83,6 +83,7 @@
             <property name="tooltip-column">3</property>
             <property name="search-column">0</property>
             <property name="enable-search">True</property>
+            <property name="enable-grid-lines">vertical</property>
             <signal name="row-activated" handler="row_activated"/>
             <child>
               <object class="GtkTreeViewColumn">

gtk/inspector/resource-list.ui

@@ -87,6 +87,7 @@
                     <property name="visible">True</property>
                     <property name="model">model</property>
                     <property name="enable-search">False</property>
+                    <property name="enable-grid-lines">vertical</property>
                     <signal name="row-activated" handler="row_activated"/>
                     <child internal-child="selection">
                       <object class="GtkTreeSelection">

gtk/inspector/selector.ui

@@ -27,6 +27,8 @@
             <property name="visible">True</property>
             <property name="model">model</property>
             <property name="enable-search">False</property>
+            <property name="show-expanders">False</property>
+            <property name="level-indentation">18</property>
             <child>
               <object class="GtkTreeViewColumn">
                 <property name="title" translatable="yes">Selector</property>

gtk/inspector/signals-list.ui

@@ -85,6 +85,7 @@
                 <property name="visible">True</property>
                 <property name="model">model</property>
                 <property name="enable-search">False</property>
+                <property name="enable-grid-lines">vertical</property>
                 <child>
                   <object class="GtkTreeViewColumn">
                     <property name="title" translatable="yes">Name</property>