Add `proxy_ca_certificate_file` output to `start-proxy` action #6760

Job	Run time
Packaging: Action input (macos-latest, linked)	1m 12s
Packaging: Action input (ubuntu-latest, default)	1m 11s
Packaging: Action input (windows-latest, linked)	6m 9s
Packaging: Action input (ubuntu-latest, linked)	1m 6s
Packaging: Action input (macos-latest, nightly-latest)	1m 42s
Packaging: Action input (macos-latest, default)	1m 13s
Packaging: Action input (windows-latest, nightly-latest)	6m 53s
Packaging: Action input (ubuntu-latest, nightly-latest)	1m 19s
Packaging: Action input (windows-latest, default)	6m 8s
	26m 53s

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