Obtain fuzzing constants from method annotations

[EgorkaKulikov]

Description

Current implementation of Fuzzer allows to collect constants that can be found in Jimple body only. However, there are some additional sources of useful values, that can not be found in Soot - for example, method annotations.

Expected behaviour

Consider the following code snippet:

@GetMapping("/api/foos")
@ResponseBody
public String getFoos(@RequestParam(defaultValue = "test") String id) {
    return "ID: " + id;
}

The constant test should be collected for further test generation.

Context

Maxim says we can collect this constants not only from ExceptionalUnitGraph, this is ok for him.