initrd-generator: support rd.net.dns-backend and rd.net.dns-resolve-mode
Summary
(Note: the first 3 commits are from !2096 (merged), any comment about them should be done on that MR).
Add support for two new command line arguments:
-
rd.net.dns-backend
used to control the "dns" option in NetworkManager configuration; -
rd.net.dns-resolve-mode
used to control the "resolve-mode" in the global DNS configuration.
The use case for them is the installation of a new system where the administrator wants to configure aspects of the DNS resolution starting from the early boot, for example to enable DNS over TLS and avoid that any query goes out unencrypted.