[GATEWAY] Makefile target added to send relays to grove gateway

[ezeike]

Summary

Added a Makefile target to send a relay to the grove staging gateway.

Issue

To make it convenient to send test relays to the grove gateway.

Type of change

Select one or more:

• [X] New feature, functionality or library
• [ ] Bug fix
• [ ] Code health or cleanup
• [ ] Documentation
• [ ] Other (specify)

[Olshansk]

@ezeike I updated it for you again, but please update the metadata. The PR template literally asks for it: https://raw.githubusercontent.com/pokt-network/poktroll/main/.github/pull_request_template.md

[Olshansk]

@ezeike Make sure to re-request review when it's ready for another look.