Add `browser.study.searchSeenTelemetry`

[motin]

With Pioneer configured, the telemetry archive only stores the encrypted payloads. The PR includes a new studySetup config option telemetry.internalTelemetryArchive:

    // Keep an internal telemetry archive. Useful for verifying payloads of Pioneer studies without risking actually sending any unencrypted payloads [default if omitted: false]
    internalTelemetryArchive: false,

The updated functional tests use this to verify the sent payloads. Currently only exposed via browser.studyDebug.getInternals(), this could favorably be exposed as browser.study.searchSeenTelemetry (compare to the existing browser.study.searchSentTelemetry which searches the telemetry archive)