Add Ubuntu 24.04 LTS Noble N.

Add Ubuntu 24.04 LTS "Noble Null" (the animal name is not known yet).
The release date is taken from the release schedule [1]. The end of
standard support is assumed to be end of May 2029 and ESM is assumed to
be exactly 10 years.

[1] https://discourse.ubuntu.com/t/noble-n-release-schedule/35649


Signed-off-by: Benjamin Drung <[email protected]>