depends: switch to secure download of all dependencies

Summary:

Some dependency sources were downloaded via http, even though https
(SSL/TLS) options are available.
Even if we potentially check the integrity of the downloaded files via
hash comparison, we should make use of this additional security layer.

Backport of core PR16049.

Depends on D5504.

Test Plan: Run the Gitian build twice, check the result is deterministic.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D5513