Add support for function call trace in the interpreter

This MR keeps track of function calls in the interpreter, so that a "trace" can be printed when there was some failure.

Example:

$ ligo test src/test/contracts/negative/interpreter_tests/test_trace.mligo 
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 3, characters 5-24:
  2 |   if x < 0 then
  3 |     (failwith "negative" : int)
  4 |   else

Test failed with "negative"
Trace:
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 5, characters 4-13 ,
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 5, characters 4-13 ,
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 5, characters 4-13 ,
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 5, characters 4-13 ,
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 5, characters 4-13 ,
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 9, characters 39-46 ,
File "src/test/contracts/negative/interpreter_tests/test_trace.mligo", line 9, characters 14-49

for

let rec j (x : int) : int =
  if x < 0 then
    (failwith "negative" : int)
  else
    j (x - 1)

let g (x : int) = x

let test_me = (fun (f : int -> int) -> f (g 4)) j

• has a changelog entry