Altium: Apply symbol orientation and mirroring on import

Apply the symbol orientation and mirroring from Altium schematic files
when importing. Previously, all imported symbols were placed at 0 degree
rotation regardless of their original orientation in Altium.

The orientation mapping follows the same pattern used for power ports:
- Altium 0 (RIGHTWARDS) -> KiCad SYM_ORIENT_90
- Altium 1 (UPWARDS) -> KiCad SYM_ORIENT_180
- Altium 2 (LEFTWARDS) -> KiCad SYM_ORIENT_270
- Altium 3 (DOWNWARDS) -> KiCad SYM_ORIENT_0

When the symbol is mirrored in Altium, SYM_MIRROR_Y is also applied.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/19630

eeschema/sch_io/altium/sch_io_altium.cpp

@@ -1665,8 +1665,21 @@ void SCH_IO_ALTIUM::ParseComponent( int aIndex, const std::map<wxString, wxStrin
     for( SCH_FIELD& field : symbol->GetFields() )
         field.SetVisible( false );
 
-    // TODO: keep it simple for now, and only set position.
-    // component->SetOrientation( elem.orientation );
+    int orientation = SYMBOL_ORIENTATION_T::SYM_ORIENT_0;
+
+    switch( elem.orientation )
+    {
+    case 0: orientation = SYMBOL_ORIENTATION_T::SYM_ORIENT_90;  break;
+    case 1: orientation = SYMBOL_ORIENTATION_T::SYM_ORIENT_180; break;
+    case 2: orientation = SYMBOL_ORIENTATION_T::SYM_ORIENT_270; break;
+    case 3: orientation = SYMBOL_ORIENTATION_T::SYM_ORIENT_0;   break;
+    default: break;
+    }
+
+    if( elem.isMirrored )
+        orientation += SYMBOL_ORIENTATION_T::SYM_MIRROR_Y;
+
+    symbol->SetOrientation( orientation );
 
     // If Altium has defined a library from which we have the part,
     // use this as the designated source library.