Pass recvTime to uplink decoder for TS013 compatibility

[johanstokking]

Summary

Application Server does not pass recvTime in the input object to the uplink decoder. This is required for compliance with TS013. See https://resources.lora-alliance.org/technical-specifications/ts013-1-0-0-payload-codec-api.

Current Situation

The codecs are TS013 compliant except for this recvTime field.

Why do we need this? Who uses it, and when?

We need it for TS013 compliance. The field is there for the codecs to insert metadata or even decode data based on time.

Proposed Implementation

1. Add recvTime to https://github.com/TheThingsNetwork/lorawan-stack/blob/v3.33/pkg/messageprocessors/javascript/javascript.go#L172-L175. In JavaScript it should be Date, probably time.Time is converted by goja, otherwise we need some conversion in the wrapper script
2. Pass the recvTime to the function in https://github.com/TheThingsNetwork/lorawan-stack/blob/v3.33/pkg/messageprocessors/javascript/javascript.go#L203-L205
3. Add unit tests
4. Update documentation: https://www.thethingsindustries.com/docs/integrations/payload-formatters/javascript/uplink/

Contributing

• I can help by doing more research.
• I can help by implementing the feature after the proposal above is approved.
• I can help by testing the feature before it's released.

Validation

• The feature is tested in a staging environment.
• The feature is documented in The Things Stack Documentation

Code of Conduct

• I agree to follow TTN's Community Code of Conduct.