Don't allow project files to be renamed or deleted in project tree pane.

This prevents any potential breakage of a project due to the file changes.
It is overly zealous because the project manager doesn't actually have any
knowledge of which files belong to the project.

Fixes: https://gitlab.com/kicad/code/kicad/-/issues/9654

kicad/project_tree_item.cpp

@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 1992-2020 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 1992-2021 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -72,6 +72,26 @@ void PROJECT_TREE_ITEM::SetState( int state )
 }
 
 
+bool PROJECT_TREE_ITEM::CanDelete() const
+{
+    if( m_type == TREE_FILE_TYPE::DIRECTORY
+        || m_type == TREE_FILE_TYPE::LEGACY_PROJECT
+        || m_type == TREE_FILE_TYPE::JSON_PROJECT
+        || m_type == TREE_FILE_TYPE::LEGACY_SCHEMATIC
+        || m_type == TREE_FILE_TYPE::SEXPR_SCHEMATIC
+        || m_type == TREE_FILE_TYPE::LEGACY_PCB
+        || m_type == TREE_FILE_TYPE::SEXPR_PCB
+        || m_type == TREE_FILE_TYPE::DRAWING_SHEET
+        || m_type == TREE_FILE_TYPE::FOOTPRINT_FILE
+        || m_type == TREE_FILE_TYPE::SCHEMATIC_LIBFILE
+        || m_type == TREE_FILE_TYPE::SEXPR_SYMBOL_LIB_FILE
+        || m_type == TREE_FILE_TYPE::DESIGN_RULES )
+        return false;
+
+    return true;
+}
+
+
 const wxString PROJECT_TREE_ITEM::GetDir() const
 {
     if( TREE_FILE_TYPE::DIRECTORY == m_type )
@@ -84,7 +104,7 @@ const wxString PROJECT_TREE_ITEM::GetDir() const
 bool PROJECT_TREE_ITEM::Rename( const wxString& name, bool check )
 {
     // this is broken & unsafe to use on linux.
-    if( m_type == TREE_FILE_TYPE::DIRECTORY )
+    if( !CanRename() )
         return false;
 
     if( name.IsEmpty() )
@@ -128,6 +148,9 @@ bool PROJECT_TREE_ITEM::Rename( const wxString& name, bool check )
 
 void PROJECT_TREE_ITEM::Delete()
 {
+    if( !CanDelete() )
+        return;
+
     wxString errMsg;
 
     if( !KIPLATFORM::ENV::MoveToTrash( GetFileName(), errMsg ) )

kicad/project_tree_item.h

@@ -80,6 +80,16 @@ public:
     void Activate( PROJECT_TREE_PANE* aTreePrjFrame );
     void SetState( int state );
 
+    /**
+     * Determine if a file can be deleted via the project tree pane.
+     *
+     * @note Any of the files that could potentially break a project are flagged as cannot delete
+     *       or rename.
+     *
+     * @return false if the file managed by this item cannot be deleted or true if it can.
+     */
+    bool CanDelete() const;
+    bool CanRename() const { return CanDelete(); }
 
 private:
     TREE_FILE_TYPE  m_type;         // = TREE_PROJECT, TREE_DIRECTORY ...

kicad/project_tree_pane.cpp

@@ -642,6 +642,9 @@ void PROJECT_TREE_PANE::onRight( wxTreeEvent& Event )
             continue;
         }
 
+        can_delete = item->CanDelete();
+        can_rename = item->CanRename();
+
         wxString full_file_name = item->GetFileName();
 
         switch( item->GetType() )
@@ -653,7 +656,6 @@ void PROJECT_TREE_PANE::onRight( wxTreeEvent& Event )
             if( item->GetId() == m_TreeProject->GetRootItem() )
             {
                 can_switch_to_project = false;
-                can_delete = false;
             }
             else
             {
@@ -665,7 +667,6 @@ void PROJECT_TREE_PANE::onRight( wxTreeEvent& Event )
         case TREE_FILE_TYPE::DIRECTORY:
             can_switch_to_project = false;
             can_edit = false;
-            can_rename = false;
             break;
 
         default: