Display notification about not yet processed data also when visits log is disabled

[sgiehl]

Description:

When viewing data for a period that includes today, we are currently displaying a notification if no archive data is available yet, but there has been raw data tracked already.

This currently does not work when the visits log is disabled in config or only for the current site, as we are checking for raw data availability using the API method Live.getLastVisitsDetails. But this one is disabled when the visits log is not available.

To be able to show a similar notification when there has been raw data tracked, but the visits log is disabled, this PR introduces a new API method Live.getMostRecentVisitsDateTime, which simply returns the last actions date time that happened (in a certain period).

The check for raw data availability has been switched to use the new API method in favor of Live.getLastVisitsDetails. Same was applied to the check done on the no data page.

In case the visits log is disabled, no archives have been built yet, but raw data was tracked this notification will be shown:

fixes #19736

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed

[michalkleiner]

Was just passing by so left a few code comments, I didn't functionally check this.