design blocks: point to new lib table on project change

Fixes: https://gitlab.com/kicad/code/kicad/-/issues/19783

eeschema/design_block_tree_model_adapter.h

@@ -44,6 +44,8 @@ public:
 
     TOOL_INTERACTIVE* GetContextMenuTool() override;
 
+    void SetLibTable( DESIGN_BLOCK_LIB_TABLE* aLibs ) { m_libs = aLibs; }
+
 protected:
     /**
      * Constructor; takes a set of libraries to be included in the search.

eeschema/widgets/panel_design_block_chooser.cpp

@@ -265,6 +265,7 @@ void PANEL_DESIGN_BLOCK_CHOOSER::RefreshLibs( bool aProgress )
 
     // Read the libraries from disk if they've changed
     DESIGN_BLOCK_LIB_TABLE* fpTable = m_frame->Prj().DesignBlockLibs();
+    adapter->SetLibTable( fpTable );
 
     // Sync FOOTPRINT_INFO list to the libraries on disk
     if( aProgress )