init: remove Parser singleton and related cleanup

* Remove the Parser singleton (Hooray!)
* Rename parser.* to tokenizer.* as this is actually a tokenizer
* Rename init_parser.* to parser.* as this is a generic parser
* Move contents of init_parser_test.cpp to service_test.cpp as this
  actually is a test of the parsing in MakeExecOneshotService() and
  nothing related to (init_)parser.cpp

Test: boot bullhead
Test: bool sailfish
Test: init unit tests
Change-Id: I4fe39e6483f58ebd3ce5ee715a45dbba0acf5d91
diff --git a/init/init_test.cpp b/init/init_test.cpp
index 0a4071b..2062290 100644
--- a/init/init_test.cpp
+++ b/init/init_test.cpp
@@ -23,8 +23,8 @@
 #include "action.h"
 #include "builtins.h"
 #include "import_parser.h"
-#include "init_parser.h"
 #include "keyword_map.h"
+#include "parser.h"
 #include "util.h"
 
 namespace android {