Refactor error handling and update options for resource testing

[ziflex]

• Introduced new error types: ErrResourceAlreadyRegistered and ErrResourceNotFound.
• Updated the options struct to include multiplier and randomization factor for exponential backoff.
• Modified functions to use the new error types and updated the README with new error descriptions.
• Changed import path for the backoff package to v5.

[Copilot]

Pull Request Overview

This PR refactors error handling by introducing specific error types and updates the backoff configuration options. The changes improve error specificity and provide more control over exponential backoff behavior.

• Introduced ErrResourceAlreadyRegistered and ErrResourceNotFound error types for better error classification
• Updated backoff package to v5 and added multiplier/randomization factor configuration options
• Changed Options struct to private options and updated all references accordingly

Reviewed Changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
errors.go	Added new error types for resource registration conflicts and missing resources
options.go	Made options struct private, added multiplier and randomization factor fields with new setter functions
registry.go	Updated error handling to use new structured error types with context
waitfor.go	Updated backoff package import and applied new configuration options
go.mod	Upgraded backoff dependency to v5
waitfor_test.go	Updated test code to use new private options struct
options_test.go	Updated tests for private struct and added tests for new options
README.md	Added documentation for new error types

Comments suppressed due to low confidence (2)

waitfor.go:1

• The backoff.Retry function is being called incorrectly. The function signature expects a single error return value, but line 188 returns two values (bool, error). This should be return rsc.Test(ctx) instead of return err != nil, err.

// Package waitfor provides utilities for testing and waiting for resource availability

waitfor.go:1

• The variable err on line 191 is undefined in this scope. It should return the result of backoff.Retry directly: return backoff.Retry(...).

// Package waitfor provides utilities for testing and waiting for resource availability

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