Parser does not support _ as a decimal separator

[KronicDeth]

Using _ as a separator in long integer literals has been supported since erlang/otp#2324 in BEAM, so we should support it too.

init.erl

-module(init).
-export([start/0]).
-import(erlang, [convert_time_unit/3, display/1]).
-import(lumen, [is_small_integer/1]).

start() ->
  Time = 1_000_000_000,
  display(is_small_integer(Time)),
  FromHertz = 2,
  ToHertz = 5,
  display(convert_time_unit(Time, FromHertz, ToHertz)),
  display(convert_time_unit(Time, FromHertz, second)),
  display(convert_time_unit(Time, FromHertz, millsecond)),
  display(convert_time_unit(Time, FromHertz, nanosecond)),
  display(convert_time_unit(Time, FromHertz, native)),
  display(convert_time_unit(Time, FromHertz, perf_counter)),
  display(convert_time_unit(Time, second, ToHertz)),
  display(convert_time_unit(Time, second, second)),
  display(convert_time_unit(Time, second, millsecond)),
  display(convert_time_unit(Time, second, nanosecond)),
  display(convert_time_unit(Time, second, native)),
  display(convert_time_unit(Time, second, perf_counter)),
  display(convert_time_unit(Time, millisecond, ToHertz)),
  display(convert_time_unit(Time, millisecond, second)),
  display(convert_time_unit(Time, millisecond, millsecond)),
  display(convert_time_unit(Time, millisecond, nanosecond)),
  display(convert_time_unit(Time, millisecond, native)),
  display(convert_time_unit(Time, millisecond, perf_counter)),
  display(convert_time_unit(Time, microsecond, ToHertz)),
  display(convert_time_unit(Time, microsecond, second)),
  display(convert_time_unit(Time, microsecond, millsecond)),
  display(convert_time_unit(Time, microsecond, nanosecond)),
  display(convert_time_unit(Time, microsecond, native)),
  display(convert_time_unit(Time, microsecond, perf_counter)),
  display(convert_time_unit(Time, nanosecond, ToHertz)),
  display(convert_time_unit(Time, nanosecond, second)),
  display(convert_time_unit(Time, nanosecond, millsecond)),
  display(convert_time_unit(Time, nanosecond, nanosecond)),
  display(convert_time_unit(Time, nanosecond, native)),
  display(convert_time_unit(Time, nanosecond, perf_counter)),
  display(convert_time_unit(Time, native, ToHertz)),
  display(convert_time_unit(Time, native, second)),
  display(convert_time_unit(Time, native, millsecond)),
  display(convert_time_unit(Time, native, nanosecond)),
  display(convert_time_unit(Time, native, native)),
  display(convert_time_unit(Time, native, perf_counter)),
  display(convert_time_unit(Time, per_counter, ToHertz)),
  display(convert_time_unit(Time, per_counter, second)),
  display(convert_time_unit(Time, per_counter, millsecond)),
  display(convert_time_unit(Time, per_counter, nanosecond)),
  display(convert_time_unit(Time, per_counter, native)),
  display(convert_time_unit(Time, per_counter, perf_counter)).

Error

Compiling tests/lib/erlang/convert_time_unit_3/with_small_integer_time_valid_units_returns_converted_value/init.erl
error: unrecognized token
  ┌─ tests/lib/erlang/convert_time_unit_3/with_small_integer_time_valid_units_returns_converted_value/init.erl:7:11
  │
7 │   Time = 1_000_000_000,
  │           ^^^^^^^^^^^^ expected: "!", "#", "(", ")", "*", "+", "++", ",", "-", "--", "->", ".", "/", "/=", ":", "::", ":=", ";", "<", "<-", "=", "=/=", "=:=", "=<", "==", "=>", ">", ">=", ">>", "]", "after", "and", "andalso", "band", "bor", "bsl", "bsr", "bxor", "catch", "div", "end", "of", "or", "orelse", "rem", "when", "xor", "|", "||", "}"

error: parsing failed