Fixed

• Backend changes to networking should give slight improvements to downloads, most noticeably in search
• The 'launch' subcommand will no longer pass NRFUTIL_LOG_PREFIX to the subprocess which means that any use of nrfutil within the subprocess won't automatically log to the parent process log file and will instead have its own log file or require the NRFUTIL_LOG_PREFIX env var to be explicitly set again.
• Properly hide the --install-dir flag on macOS, as this is not supported.