By avoiding to use `broker::data` directly, we gain a degree of freedom
that allows us to swap out `broker::data` for something else (e.g.,
`broker::variant`) in the future. Furthermore, it also helps us to keep
Broker types "local" to the Broker manager and gives us a nicer
interface.
Also replaces uses of `broker::expected` with `std::optional`. While an
`expected `can carry additional information as to why a value is not
present, nothing in Zeek ever cared about that. Hence, using
`std::optional` removes an unnecessary dependency on a Broker detail
while also being more efficient (no extra heap allocation when no value
is present).
This largely copies over Spicy's `.clang-format` configuration file. The
one place where we deviate is header include order since Zeek depends on
headers being included in a certain order.
better (than nothing) run-time errors for compiled scripts
fixes for dealing with recursive types in compiled scripts
fix for values in compiled scripts containing embedded comment markers
