SetupConfig function for Unit Tests

[sampocs]

Closes: #XXX

Context and purpose of the change

When working with addresses in unit tests, we need to update the sdk config to have a stride address prefix. The function to set these config settings was already in our test utils, but it was limited to our keeper test framework. This PR makes the setup function public so it can be leveraged by non-keeper tests.

Brief Changelog

• Moved config settings out of init and into a SetupConfig function
• Added config function to apptesting so it's easily importable
• Added function to generate test addresses

Usage

import "github.com/Stride-Labs/stride/v4/app/apptesting"

apptesting.SetupConfig()
validAddr, invalidAddr := apptesting.GenerateTestAddrs()

Author's Checklist

I have...

• Run and PASSED locally all GAIA integration tests
• If the change is contentful, I either:
  • Added a new unit test OR
  • Added test cases to existing unit tests
• OR this change is a trivial rework / code cleanup without any test coverage

If skipped any of the tests above, explain.

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

I have...

• reviewed state machine logic
• reviewed API design and naming
• manually tested (if applicable)
• confirmed the author wrote unit tests for new logic
• reviewed documentation exists and is accurate

Documentation and Release Note

• Does this pull request introduce a new feature or user-facing behavior changes?
• Is a relevant changelog entry added to the Unreleased section in CHANGELOG.md?
• This pull request updates existing proto field values (and require a backend and frontend migration)?
• Does this pull request change existing proto field names (and require a frontend migration)?
  How is the feature or change documented?
  • not applicable
  • jira ticket XXX
  • specification (x/<module>/spec/)
  • README.md
  • not documented