Securely store secrets needed by the automated test suite

In our test suite we use access to email accounts or XMPP chat. We should be able to store that kins of credentials or other sensitive data (host/port/setting/keys/certificates for smtp, pop, imap, ssh/sftp, git, etc.)

Feature Branch: test/8188-better-test-suite-configuration

Parent Task: #6298 (closed)

Related issues

• Related to #8188 (closed)
• Related to #8920 (closed)
• Blocks #6304 (closed)
• Blocks #6308 (closed)

Original created by @bertagaz on 6301 (Redmine)