CNJR-2306: Make log level configurable

[szh]

Desired Outcome

Make log level configurable.
Currently there are only two options for logging: debug-logging on or off. There is a customer request to allow minimizing logs to only warnings or errors, with the option to enable info level logs as well. This will cut down on the amount of noise coming from secrets rotations, where the number of log messages will be amplified due to continual refresh.

Implemented Changes

• Added new configuration option, "LOG_LEVEL" / "conjur.org/log-level"
  • Valid options are "debug", "info", "warn", "error"
• Deprecated "DEBUG" / "conjur.org/debug-logging" configuration option

Connected Issue/Story

CyberArk internal issue ID: CNJR-2306

Changelog

• The CHANGELOG has been updated, or
• This PR does not include user-facing changes and doesn't require a
  CHANGELOG update

Test coverage

• This PR includes new unit and integration tests to go with the code
  changes, or
• The changes in this PR do not require tests

Documentation

• Docs (e.g. READMEs) were updated in this PR
• A follow-up issue to update official docs has been filed here: [insert issue ID]
• This PR does not require updating any documentation

Behavior

• This PR changes product behavior and has been reviewed by a PO, or
• These changes are part of a larger initiative that will be reviewed later, or
• No behavior was changed with this PR

Security

• Security architect has reviewed the changes in this PR,
• These changes are part of a larger initiative with a separate security review, or
• There are no security aspects to these changes

[gl-johnson]

Just a small comment on unit tests but otherwise LGTM