Fix --apimapping with unstructured parcelables

This fix consists of several related smaller fixes:
- --apimapping accepts positions arguments as inputs.
- --apimapping is a top-level command in HELP MSG.
- FOUND_PARCELABLE is handled as error consistently when -b is set.
- typo in aidl_parser_fuzzer.dict

Previously, FOUND_PARCELABLE error was returned from
load_and_validate_aidl and handled by callers. Treating it as error or
success was not consistent in various places.

Now, FOUND_PARCELABLE is returned only if -b is turned on and it is
always treated as an error by callers.

This fixes the crash that happens when --apimapping is called with
unstructured parcelables.

Bug: 196686928
Test: aidl_unittests
Test: m
Change-Id: I95cc9cc556825dc78f975d1f092b6420ec5399f8
5 files changed