Add CLI for shadowsocks obfuscation

[dlon]

Close DES-1145.

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This change is 

[linear]

DES-1145 Add CLI for Shadowsocks

[Serock3]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @dlon)

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CHANGELOG.md line 28 at r1 (raw file):

- Add DAITA (Defence against AI-guided Traffic Analysis) setting for Linux and macOS.
- Add `--json` flag to `mullvad status` CLI.
- Add WireGuard over Shadowsocks obfuscation to the CLI.

Since this is the only way a customer could know about the feature, what do you think about elaborating a bit? Maybe mentioning what command activates it an briefly stating what it does.

E.g. "- New Shadowsocks obfuscation to help connect while under censorship. Currently only available in the CLI by running mullvad obfuscation set shadosocks --port <PORT>"

Or are we expecting the GUI part to be implemented before the next release?

[Serock3]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @dlon)

[Serock3]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved