[layouts] improve lock item(s) / unlock all toolbar icons (#5929)

Author: nirvn

images/images.qrc

@@ -249,6 +249,7 @@
         <file>themes/default/mActionLabeling.svg</file>
         <file>themes/default/mActionLocalCumulativeCutStretch.svg</file>
         <file>themes/default/mActionLocalHistogramStretch.svg</file>
+        <file>themes/default/mActionLockItems.svg</file>
         <file>themes/default/mActionLowerItems.svg</file>
         <file>themes/default/mActionMapTips.svg</file>
         <file>themes/default/mActionMeasure.svg</file>
@@ -340,6 +341,7 @@
         <file>themes/default/mActionTracing.svg</file>
         <file>themes/default/mActionUndo.svg</file>
         <file>themes/default/mActionUngroupItems.svg</file>
+        <file>themes/default/mActionUnlockAll.svg</file>
         <file>themes/default/mActionSvgAnnotation.svg</file>
         <file>themes/default/mActionWhatsThis.svg</file>
         <file>themes/default/mActionZoomActual.svg</file>

images/themes/default/mActionLockItems.svg

@@ -625,7 +625,7 @@
   <action name="mActionLockItems">
    <property name="icon">
     <iconset resource="../../../images/images.qrc">
-     <normaloff>:/images/themes/default/locked.svg</normaloff>:/images/themes/default/locked.svg</iconset>
+     <normaloff>:/images/themes/default/mActionLockItems.svg</normaloff>:/images/themes/default/mActionLockItems.svg</iconset>
    </property>
    <property name="text">
     <string>Loc&amp;k Selected Items</string>
@@ -637,7 +637,7 @@
   <action name="mActionUnlockAll">
    <property name="icon">
     <iconset resource="../../../images/images.qrc">
-     <normaloff>:/images/themes/default/unlocked.svg</normaloff>:/images/themes/default/unlocked.svg</iconset>
+     <normaloff>:/images/themes/default/mActionUnlockAll.svg</normaloff>:/images/themes/default/mActionUnlockAll.svg</iconset>
    </property>
    <property name="text">
     <string>Unl&amp;ock All</string>