unbound: Vendor import 1.19.1

Release notes at

https://www.nlnetlabs.nl/news/2024/Feb/13/unbound-1.19.1-released/

Security: CVE-2023-50387, CVE-2023-50868
Security: FreeBSD-SA-24:03.unbound
Approved by: so

(cherry picked from commit 8f76bb7dad48538c6832c2fb466a433d2a3f8cd5)
(cherry picked from commit 4f4adb0576dfbcd0d956db0146c9de7e1bb71563)
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(cherry picked from commit f5a091c1f6a068cdc5c3bd23536830de9dfe7b84)
(cherry picked from commit 6e71235e558ef579605e7f35b02f983b9a246a4a)
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(cherry picked from commit abe4ced2b9de0a3dd44d7e2068cfd7fa2b428c16)