Make Salt API endpoint authenticated and encrypted

[moio]

What does this PR change?

Makes the salt API endpoint authenticated and encrypted.

Addresses CVE-2020-8028, aka SUSE bug number 1175884

GUI diff

No difference.

Documentation

No documentation needed: only internal and user invisible changes

• DONE

Test coverage

• No tests: already covered

• DONE

Links

Fixes https://bugzilla.suse.com/show_bug.cgi?id=1175884
Tracks https://github.com/SUSE/spacewalk/pull/12276

• DONE

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_lint_checkstyle"
• Re-run test "java_pgsql_tests"
• Re-run test "schema_migration_test_oracle"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[juliogonzalez]

LGTM. Let's wait for the tests.

[juliogonzalez]

The failed test is expected, as for other PRs. Nothing to worry about.