Emit `transaction.data` inside `contexts.trace.data`

[kahest]

• find out if we already do this
• if we don't implement it like this :)

[lbloder]

@kahest We are currently sending transaction (root span) data as extra here. Should we keep that for the sake of backwards compatibility?

[kahest]

@lbloder I'm not sure, I don't have context why we do this - maybe @stefanosiano @markushi have an idea.

[stefanosiano]

@kahest We are currently sending transaction (root span) data as extra here. Should we keep that for the sake of backwards compatibility?

I'd keep it for compatibility, also because we are updating v7. We can think about removing it in v8, if it's not used by our product

[markushi]

@lbloder as discussed here, let's remove sending it as event.extra.

[adinauer]

We'll only change v8 of the SDK due to potential PII stripping issues.