add flag to show verbose output and log output under one name

[elfkuzco]

Rationale

Normalize all log outputs to be under one name instead of module specific loggers and add --debug flag for more verbose output. This is intended to be a fix for #206 .

Changes

• Initialize logger with default level of INFO instead of DEBUG
• Add --debug flag to dynamically set level to DEBUG
• When the --debug flag is set, update the handlers to have their levels set to DEBUG as a simple logger.setLevel(logging.DEBUG) only sets it for the logger and not for the handlers. This is akin to what the getLogger function from zimscraperlib does. After all, it is the handlers that handle output and not the logger object.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 16.66667% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 0.75%. Comparing base (4ac977c) to head (bfd801b).

Files	Patch %	Lines
src/gutenberg2zim/entrypoint.py	0.00%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #223 +/- ## ======================================== - Coverage 0.76% 0.75% -0.01% ======================================== Files 15 15 Lines 1575 1580 +5 Branches 341 343 +2 ======================================== Hits 12 12 - Misses 1563 1568 +5 ```

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