Adding `DEBUG_INFO` setting

I was thinking about how to improve the "debugging" process when weird things happen...

And I realized that it could be really useful to add an option to "see" what happens behind the scenes. It could be, for example, a setting called DEBUG_INFO that when True shows relevant information to help you to understand what's happening.

I was trying a little and that's what I got.

---

Input:

dateparser.parse('07/03/2009')

Log:

Interpretation: 07 - 03 - 2009
Order: month, day, year
Used locale: en

Out:

2009-07-03 00:00:00

---

Input:

dateparser.parse('2009')

Log:

Missing: Day, Month
Interpretation: 2009
Order: year
Used locale: en

Out:

2009-09-05 00:00:00

---

Input:

dateparser.parse('Feb 2009')

Log:

Missing: Day
Interpretation: february - 2009
Order: year
Used locale: en

Out:

2009-02-05 00:00:00

---

Input:

dateparser.parse('07/03/2009', locales=['fr'])

Log:

Interpretation: 07 - 03 - 2009
Order: day, month, year
Used locale: fr

Out:

2009-03-07 00:00:00

---

Input:

dateparser.parse('en 2 días')

Log:

Used locale: es

Out:

2019-09-07 17:46:02.653798

Of course there are a lot of new information that could appear in the log, that's just an idea.

What do you think?

Review the issue's proposed DEBUG_INFO examples and determine the intended scope of the setting, including which parsing details it should expose and how users would enable it. Before implementation, define acceptance criteria for the logged information and its output behavior; the issue names no files or tests to run.