docs(playwright-engine): add UI and CLI guides and migration recipe #6507

Job	Run time
Build docker image	5m 43s
config-e2e	1s
Agent unit tests	1m 0s
CLI unit tests	37s
API Server unit tests	2m 30s
WebUI unit tests	2m 4s
Test examples (collector)	45s
CLI e2e tests (8, 0)	1m 27s
WebUI End-to-end tests (1)	3m 44s
CLI smoke tests (local)	44s
CLI e2e tests (8, 1)	1m 26s
WebUI End-to-end tests (2)	2m 34s
CLI smoke tests (docker)	46s
CLI e2e tests (8, 2)	1m 22s
Test examples (tracetest-jaeger)	47s
WebUI End-to-end tests (3)	2m 33s
CLI e2e tests (8, 3)	1m 20s
Test examples (tracetest-opensearch)	7m 27s
WebUI End-to-end tests (4)	2m 35s
CLI e2e tests (8, 4)	1m 23s
Test examples (tracetest-tempo)	44s
WebUI End-to-end tests (5)	2m 37s
Tracetesting API Server (InMemory)	3m 59s
CLI e2e tests (8, 5)	2m 43s
Test examples (tracetest-provisioning-env)	44s
WebUI End-to-end tests (6)	2m 29s
CLI e2e tests (8, 6)	1m 35s
WebUI End-to-end tests (7)	2m 33s
CLI e2e tests (8, 7)	3m 35s
WebUI End-to-end tests (8)	2m 32s
Tracetesting API Server (NATS)	3m 54s
	1h 8m 13s

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