LibWeb: Move SVG::PathDataParser into its own file and rename it

I've chosen the name `AttributeParser` since it parses data from
attributes. Rather than duplicate the parsing of numbers and other
basic types, let's make use of this existing parsing code for parsing
the data for `<line>`, `<polyline>`, etc.

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -265,6 +265,7 @@ set(SOURCES
     RequestIdleCallback/IdleDeadline.cpp
     ResizeObserver/ResizeObserver.cpp
     SVG/AttributeNames.cpp
+    SVG/AttributeParser.cpp
     SVG/SVGElement.cpp
     SVG/SVGGElement.cpp
     SVG/SVGGeometryElement.cpp