Use json encoding for cquery ParseResult

also using a generic json_encode as an approximation for `json.encode`

Test: 1. use m --bazel-mode-dev nothing to verify no error occured. 2.
revise the test cases under request_type_test. 3. pass the test cases

Bug:242587802

Change-Id: I1288ecca1afd3e32f6473bcabae4ee2cb5838007