Report Nimbus Schemas package version in telemetry

[data-sync-user]

There are 6 mobile clients currently supported by Nimbus:

https://github.com/mozilla/experimenter/blob/main/app/experimenter/experiments/constants/nimbus.py#L49-L128

and reasoning about which version of the Nimbus Shared Schema defined here:

https://github.com/mozilla/nimbus-shared/blob/main/types/experiments.ts

is supported by a given version of a given mobile client can be difficult.

We need to track which version of which client supports some given version of the schema to know which schema to emit from Experimenter as the schema changes over time, so one way to approach that could be to emit the combination of

(app identifier, app channel, app version, nimbus shared schema package version)

in each clients telemetry and then we could know

• Which future clients will support new schema changes (as they land in nightly and begin reporting telemetry)
• Which past clients are still using old schema versions (as they lag behind new releases)

Can we add something to the mobile nimbus client that

• Determines the currently used mozilla nimbus shared package version
• Emits that in telemetry

┆Issue is synchronized with this Jira Task