OpenTelemetry Plugins should have a way to modify Resource and Scope for metrics and traces

[nortenorte]

Is your feature request related to a problem? Please describe.
Originally this was submitted in #8206 and was implemented for logs only in #8989. We would like to be able to use the same for traces and metrics as well. #8206 was closed even it was only partially implemented.

Describe the solution you'd like
See #8206.

Describe alternatives you've considered
N/A

Additional context
We would like to be able to modify for the same reasons as for logs.