scrooge-generator: Resolve self referencing types.

Problem

Scrooge currently doesn't support self-referencing types. This is
useful for a number of cases.

Solution

Change the type resolver's scope to include the current type. Add unit
tests.

Result

Self-referencing types no longer result in TypeNotFoundException.
This should resolve #243 and
partially resolve #160. This
change doesn't yet support recursive types which is needed to fully
resolve #160.

This should be a backward compatible change since all the thrift files
that are resolved correctly now will continue to get resolved
correctly.

One caveat though is that we don't enforce the self-reference type to
be optional or collection type. We just depend on the generated`
language's compiler to enforce that (i.e. we expect that compiler to
generate an error if a self-referencing type is specified as
required).

Signed-off-by: Kevin Oliver <koliver@twitter.com>

RB_ID=873802

CHANGES

@@ -5,6 +5,9 @@ as it is included in Scrooge's user's guide.
 4.x
 -----
 
+- Add support for self-referencing types from `pinsri` via
+  https://github.com/twitter/scrooge/pull/244 ``RB_ID=``
+
 - scrooge: Remove unmaintained bin/ directory. ``RB_ID=873411``
 
 4.10.0

scrooge-generator-tests/src/test/resources/gold_file_input/gold.thrift

@@ -21,6 +21,8 @@ struct Request {
   1: list<string> aList,
   2: set<i32> aSet,
   3: map<i64, i64> aMap,
+  4: optional Request aRequest,
+  5: list<Request> subRequests
 }
 
 struct Response {