Pass chunk information in .FromData context

[rgmz]

Continuation of trufflesecurity#2228

Something like this, except this only works for GitHub scans.

diff --git a/pkg/engine/engine.go b/pkg/engine/engine.go
index 0e796e56b..5e20a9329 100644
--- a/pkg/engine/engine.go
+++ b/pkg/engine/engine.go
@@ -1113,6 +1113,10 @@ func (e *Engine) detectChunk(ctx context.Context, data detectableChunk, scanEnti
                detectBytesPerMatch.Observe(float64(len(matchBytes)))

                ctx, cancel := context.WithTimeout(ctx, detectionTimeout)
+               metadata := data.chunk.SourceMetadata.GetGithub()
+               ctx = context.WithValues(ctx,
+                       "link", metadata.GetLink(),
+               )
                t := time.AfterFunc(detectionTimeout+1*time.Second, func() {
                        ctx.Logger().Error(nil, "a detector ignored the context timeout", "metadata", data.chunk.SourceMetadata.GetData())
                })