Extend hidl_parser with support for structs and enum value expansion

This adds support for hidl_parser to extract structs from HIDL interface files (incl. nested structs)
It also adds the ability for (a subset of) enum value descriptions to resolve themselves to numeric data:
 - decimal and hexadecimal constants
 - value | value
 - value << value
 - references to other elements of the same enum
 - references to elements of other enums in the same file

Test: manual testing

Change-Id: I8a78cd88b5be841648d81ab152953a90af365a98
1 file changed