Adding some metrics requested by customers

[snake14]

Description:

Customers have been requesting some metrics be made available in CustomReports, so this PR is trying to add some of those.

Metrics being added:

• Average product quantity
• Average product price
• Product Revenue (Total & avg)
• Total click outlinks
• Product Category (Dimension)
• Total content interactions (Entries with Content Interaction)
• Content interaction rate

Internal ticket: PG-3658

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

[snake14]

Converting to draft because it looks like my latest commit broke some tests.

[sgiehl]

@snake14 In general it would be good to split up the PR into one PR per metric you want to add and where possible add a test for it. That makes it easier to review and merge it step by step.

Note: Time on page won't work that way, as that metric isn't tacked as a normal dimension. Instead it also stores the id of the previous action the stored time is actually valid for. This can't be achieved with a SQL query.

[snake14]

@snake14 In general it would be good to split up the PR into one PR per metric you want to add and where possible add a test for it. That makes it easier to review and merge it step by step.

Note: Time on page won't work that way, as that metric isn't tacked as a normal dimension. Instead it also stores the id of the previous action the stored time is actually valid for. This can't be achieved with a SQL query.

Thank you @sgiehl . I'll remove the time on page metrics. I've been using my CustomReports PR to test most of the metrics.

[snake14]

@sgiehl I'm not finding any good examples of testing new metrics in this repo. Could you please point me in the right direction? Do I mock a new report or something?

[snake14]

Closing in favour of https://github.com/innocraft/plugin-CustomReports/pull/240