Add BTCPay Host Onion capability

[MaxHillebrand]

Follow up to #40.

Currently I cannot set a v3 onion of a BTCPay in the BTCPayserver External Service Data / BTCPay Host Url.

[Kixunil]

I believe you have to click that "Authorize Client" link first and follow the procedure.

[BitizenOne]

@MaxHillebrand Are you running BTCPay through docker?

[MaxHillebrand]

No, a deb package from https://github.com/debian-cryptoanarchy/cryptoanarchy-deb-repo-builder/

[BitizenOne]

Interesting, I'll have to check out that project. I'm not sure how the architecture works, but using a containerized btcpayserver, I was able to connect external services through tor using a similar technique that I used here: #96 (comment)