webui: analytics module: show stored data per jobname in treemap

[fbergkemper]

This PR introduces an analytics module into webui. The first feature of this new module
is a visualization of stored backup job data in a treemap.

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[pstorz]

Good work.

• Do we want/need to have some docs about the new analytics module?
• The CHANGELOG.md commit is missing.

[fbergkemper]

Good work.

* Do we want/need to have some docs about the new analytics module?

I don't think so, because the treemap is actually self-explanatory for users.

* The CHANGELOG.md commit is missing.

I'll add it after rebase and solving merge conflicts due to some pending PRs that will be merged first, I guess.

[fbergkemper]

After a second thought and look about docs, we should add the new module here https://docs.bareos.org/IntroductionAndTutorial/BareosWebui.html#command-acl-requirements due to command.csv changes.

Going to add an extra commit for that.

[pstorz]

Good work!