WIP: Log measurements for project Import export api

This MR will use the measurements from import and export service layer, and log those measurements in structured (JSON) format in the new log file import_export.log.

This means we'd be able to take measurements via our performance CI pipeline, which is currently based on API integration, not rake tasks. Since we will use a structured JSON log instead of logging plain text to stdout, these logs could be indexed by Kibana...

Related to: #213100 (closed)

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Note This MR introduces new import-export.log file:

• Additional steps when introducing new log file

DO NOT MERGE

Blocked by: !30734 (merged)

!29905 (comment 333846154)