Make IfcParseExamples buildable outside of the main build tree

It's a very verbose version of consuming IfcOpenShell cmake package, but we'll be able to use it as a start point to build upon.

src/examples/README.md

@@ -0,0 +1,22 @@
+
+Example of building IfcParseExamples outside of the IfcOpenShell build tree.
+
+```powershell
+$IFCOPENSHELL_ROOT="L:\Projects\Github\IfcOpenShell"
+$PREFIX_PATH="$IFCOPENSHELL_ROOT\_deps\boost_1_86_0\stage\vs2022-x64"
+$PREFIX_PATH+=";$IFCOPENSHELL_ROOT\_installed-vs2022-x64"
+$PREFIX_PATH+=";$IFCOPENSHELL_ROOT\_deps-vs2022-x64-installed\rocksdb"
+$PREFIX_PATH+=";$IFCOPENSHELL_ROOT\_deps-vs2022-x64-installed\zstd"
+$PREFIX_PATH+=";L:\Software\usr\libxml2"
+
+cmake .. -G Ninja -DCMAKE_PREFIX_PATH="$PREFIX_PATH" -DCMAKE_BUILD_TYPE=Release
+ninja -v
+./IfcParseExamples.exe "../IfcParseExamples_test.ifc"
+# Scanning file...
+# Done scanning file
+# Done resolving references
+# Found 3 elements in ..\IfcParseExamples_test.ifc:
+# #182=IfcBuildingElementPart('0fmaoBJgz0kPBavO$EJkPn',#181,'Cube',$,$,#193,#183,$)
+# #111=IfcWall('1lfiJzSCH1a8vjDuSLL4Ii',#110,'Cube',$,$,#119,#114,$)
+# #150=IfcWindow('1eE0btB_54tBL59wLXKO1B',#149,'Cube',$,$,#188,#151,$,$,$)
+```