Improve the testability of MessageStore

[cquirosj]

This change introduces a targeted approach to improve the testability of MessageStore:

• Created a new ConfigurationStore as a Pinia store to replace the usage of useConfiguration composable in MessageStore
• Created a new EditRetryStore as a Pinia store to replace useEditAndRetry composable usage in MessageStore
• Removed automatic initialization in the store definition to avoid network calls during tests and take advantage of Pinia testing infrastructure that stubs actions by default and allows tests to patch the stores state instead for each scenario
• The Message store explicitly calls loadConfig() of the new stores during initialization, which in turn is stubbed by Pinia when used in tests
• This allows component tests to run without unwanted network calls, for when patching the store state is the technique the developer writing component tests prefers to use for setting up scenarios preconditions
• The original useConfiguration composable remains untouched for other components

This focused refactoring prevents network calls from being made during tests while minimizing changes to the codebase. It only affects MessageStore.ts without requiring a broader refactoring across all components that use configuration data. In the future, the rest of the application can take advantage of the new Configuration Pinia store.