In order to generate OpenTelemetry traces of the main work that OpenTofu
Core does we'll need to be able to propagate the active trace context into
the main "Execute" method of each graph node, since that's where we
typically make requests to providers, and other such work that could take
a noticeable amount of time.
Changing these frequently-used interfaces is always a noisy diff, so this
commit intentionally focuses only on changing the signature of that
interface and its one caller, and then dealing with all of the fallout of
that on existing unit test code.
For any use of Execute that was affected by this change we'll also switch
to our newer naming scheme of using "evalCtx" as the name of the
tofu.EvalContext variable, in preparation for using "ctx" idiomatically to
refer to context.Context. However, the implementations currently don't yet
name their context.Context argument because the method bodies don't yet
make use of it. We'll name each of those arguments to "ctx" individually
as we gradually add tracing support to each graph node type.
Signed-off-by: Martin Atkins <mart@degeneration.co.uk>
