Auto merge of #20307 - csmoe:measure_query_time, r=jdm

Measure time required before a layout query is serviced by the layout thread

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- [X] extract QueryMsg from ReflowGoal
- [X] introduce QueryMsg timestamp

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [x] These changes fix #19795 (github issue number if applicable).

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