Feature: add verbosity option and improve log

[Guts]

ℹ️ this PR supersedes the #155

Context

Recently, we faced an issue with the log length using qgis-plugin-ci on GitLab CI/CD:

Job's log exceeded limit of 4194304 bytes.
Job execution will continue but no more output will be collected.

See this job: https://gitlab.com/Oslandia/qgis/ign-geotuileur/-/jobs/3056269109

But I've been thinking for a long time that we should reduce the amount of information returned to the terminal or let the end-user pick.

Proposed 'log policy'

Meant to be added to contributing guidelines.

• print to systematically display information to the CLI end-user and which doesn't require some log filter or format. And mark the statement with # noqa: T2 to avoid flake8 alerts. Example: Plugin archive created: qtribu.0.15.0-beta2.zip (Size: 731.37 Ko)

• logger.error for blocking issues or interrupted process. If the case is predictable and predicted, do not raise brutal exception to avoid hard readable trace in terminal. Example:

  logger.error(err_msg, exc_info=UncommitedChanges())
  sys.exit(1)

  2022-09-22 14:47:25||ERROR||release||You have uncommitted changes. Stash or commit them or use -c / --allow-uncommitted-changes option.
  qgispluginci.exceptions.UncommitedChanges

• logger.warning for annoying or imperfect but not blocking situations . Example: 2022-09-22 14:45:01||WARNING||parameters||Homepage is not given in the metadata. It is a mandatory information to publish the plugin on the QGIS official repository.

• logger.info for normal message during the process.

• logger.debug for detailed message during specific steps. example: list of zipped files, etc.

Changes

STILL IN PROGRESS

• add a verbosity option -v with an incremental count

  # by default, log nothing except print statement = WARNING
  qgis-plugin-ci package latest
  # -v = INFO
  qgis-plugin-ci -v package latest
  # -vv = DEBUG
  qgis-plugin-ci -vv package latest

• add a setting into the setup.cfg to customize log format. Default: %(asctime)s||%(levelname)s||%(module)s||%(message)s - OPTION STILL NOT IMPLEMENTED

• remove option alias -v from the version option to avoid conflict

• improve some exception handling: mainly add Trace: {exc} and use f-string instead of format as recommended

• add some volontary print statements (typically to conclude each successful command)

• add flake8-print as development requirement to enforce the lg policy. Use # noqa: T2 for relevant print statements