LibURL/Pattern: Implement processing a URL Pattern Init

This gets us to the point just before the point of parsing the
pattern strings for each URL component to produce a regular
expression.

Libraries/LibURL/CMakeLists.txt

@@ -9,6 +9,7 @@ set(SOURCES
     ${PUBLIC_SUFFIX_SOURCES}
     Pattern/Canonicalization.cpp
     Pattern/ConstructorStringParser.cpp
+    Pattern/Init.cpp
     Pattern/Pattern.cpp
     Pattern/String.cpp
     Pattern/Tokenizer.cpp