Fix import graphics routines and tests

The returns of KiCad file extensions on GTK contain basic regex matching
case-insensitive file extensions.  We need to match these in the
provider and tests

pcbnew/import_gfx/graphics_import_mgr.cpp

@@ -27,6 +27,7 @@
 #include "dxf_import_plugin.h"
 #include "svg_import_plugin.h"
 
+#include <wx/regex.h>
 
 GRAPHICS_IMPORT_MGR::GRAPHICS_IMPORT_MGR( const TYPE_LIST& aBlacklist )
 {
@@ -71,10 +72,12 @@ std::unique_ptr<GRAPHICS_IMPORT_PLUGIN> GRAPHICS_IMPORT_MGR::GetPluginByExt(
 
         for( const auto& fileExt : fileExtensions )
         {
-            if( aExtension.IsSameAs( fileExt, false ) )
+            wxRegEx extensions( fileExt, wxRE_BASIC );
+
+            if( extensions.Matches( aExtension ) )
                 return plugin;
         }
     }
 
     return {};
-}
+}

qa/pcbnew/test_graphics_import_mgr.cpp

@@ -29,6 +29,8 @@
 #include <import_gfx/graphics_import_mgr.h>
 #include <import_gfx/graphics_import_plugin.h>
 
+#include <regex>
+
 /**
  * Declares a struct as the Boost test fixture.
  */
@@ -38,7 +40,15 @@ static bool pluginHandlesExt( const GRAPHICS_IMPORT_PLUGIN& aPlugin, const std::
 {
     const auto exts = aPlugin.GetFileExtensions();
 
-    return std::find( exts.begin(), exts.end(), wxString( aExt ) ) != exts.end();
+    for( auto ext : exts )
+    {
+        std::regex ext_reg( ext.ToStdString() );
+
+        if( std::regex_match( aExt, ext_reg ) )
+            return true;
+    }
+
+    return false;
 }
 
 struct TYPE_TO_EXTS