add basic support for starting arti with obfs4proxy in managed mode

This MR adds basic support for starting arti with optional support to connect to tor over obfs4proxy in managed mode.

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I've also updated the sample app to use arti + ofbs4proxy in managed mode. It's in a separate branch because I didn't want to merge obfs4proxy binaries into the upstream repo.

sample branch: https://gitlab.com/uniqx/arti-mobile-ex/-/tree/managed-pt-obfs4proxy-sample

sample changes: https://gitlab.com/uniqx/arti-mobile-ex/-/compare/managed-pt-obfs4proxy...managed-pt-obfs4proxy-sample?from_project_id=43374908&straight=false

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closes #1 (closed)