In order to allow automatic migration to the feature level 'parent',
introduce a way to force writing signed references, even if the
user-controlled refs are unchanged.
To detect the special case of a Signed References history with a single
and root commit (which would otherwise be detected as feature level
'parent', even though the `refs/rad/sigrefs-parent` ref cannot be
written), keep information about the parent commit in `SignedRefs`.
The output of `rad inspect --sigrefs` is changed to match the more
strict interpretation of the feature level for histories with a single
and root commit.
The previous implementation used 'all' as the default for scope, this
could lead to surprising behaviour where a user would fetch all
references for cloned and seeded repositories. Instead have a progressive,
safe by default value - where it fetches only 'followed' references. Later
a user can decide to set the scope to 'all'. NOTE: the default policy
scope was not changed from 'all' and is intended to be changed at a
later date.
Pay more attention to when a Node ID is displayed in compact form. As
this was sometimes used to save space, e.g. in `rad node status` in
combination with long node addresses (like .onion names), also implement
a compact format for node addresses and use that instead in some cases.
Progress notifications in spinners keep the short form.