Allow importing more than 100 devices using the CLI tool

[vlasebian]

Summary

Importing more than 100 devices using the CLI tool is restricted by rate limiting. It would be useful for a user to be able to import a larger number of devices without splitting the import file into smaller ones and processing each file separately.

Current Situation

When trying to import a large number of end devices from the CLI tool, rate limiting restricts this at 100 devices:

error:pkg/ratelimit:rate_limit_exceeded (rate limit of `100` accesses per minute exceeded for resource `grpc:method:/ttn.lorawan.v3.DeviceRepository/GetTemplate::token:E5MPAAJ5S3PHGJREBBPOPJRHLEPEUDKHR2CEIHI`)
    rate=100

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

This is feature would be used by users when importing a large number of end devices into The Things Stack. It simplifies the process of importing end devices.

Proposed Implementation

Add a pause & retry for the CLI tool when a rate limiting error is received.

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.

[KrishnaIyer]

Importing more than 100 devices using the CLI tool is restricted by rate limiting

100 is a magic number set on TTS Cloud/Sandbox clusters and is subject to change. Indeed as you mentioned in the issue, this should not consider the number of requests but backoff based on the HTTP rate-limitd (429) response.

[KrishnaIyer]

This is a good one for @happyRip with his operational experience.