Merge pull request #28132 from rpigott/dhcp-captive-portal

Implement RFC8910: captive portal dhcp options

diff --cc man/systemd.network.xml
Simple merge

diff --cc src/basic/string-util.h
Simple merge

diff --cc src/libsystemd-network/ndisc-router.c
Simple merge

diff --cc src/libsystemd-network/sd-dhcp6-lease.c
Simple merge

diff --cc src/network/networkd-network.c
Simple merge

diff --cc test/test-network/systemd-networkd-tests.py
Simple merge