Add metadata retrieved from the `context` to the user agent when a new HTTP client is created #4944

Job	Run time
run-determination	1s
check-style (./)	30s
check-config (./)	13s
check-outdated (./)	14s
check-formatting (./)	18s
build (internal/arduino/discovery/discovery_client)	16s
check-license-headers (./)	23s
build (rpc/internal/client_example)	25s
build (commands/term_example)	20s
	2m 40s

Provide feedback