- Add `Active queries` chapter to VMUI docs
- Set `Content-Type: json` header inside promql.WriteActiveQueries() handler,
in order to be consistent with other request handlers called at app/vmselect/main.go
- Pass the request to promql.WriteActiveQueries() handler, so it can change its output
depending on the provided request params. This also improves consistency of
promql.WriteActiveQueries() args with other request hanlers at app/vmselect/main.go
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4653
* feat: add page to display a list of active queries (#4598)
* app/vmagent: code formatting
* fix: remove console
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Co-authored-by: dmitryk-dk <kozlovdmitriyy@gmail.com>