In many cases we want to expose enums for which we have the usual
xyz_to_string()/xyz_from_string() via Varlink as enums. Let's add some
infra to test the tables against each other, to automatically detect
when they deviate.
In order to implement this properly, let's export/introduce clean
json_underscorefy()/json_dashify(), for dealing with the fact that our
enums usually use dash separates ames, but Varlink doesn't allow that.
(This does not add the test cases for all enum types we expose right
now, but only adds the general infra).
It's time. sd-json was already done earlier in this cycle, let's now
make sd-varlink public too.
This is mostly just a search/replace job of epical proportions.
I left some functions internal (mostly IDL handling), and I turned some
static inline calls into regular calls.