what

Add the concept of atmos stores to the app. This PR adds only the read side of stores. The write side will be implemented in a separate PR.

why

Atmos stores allow values to be written to an external store (i.e., AWS SSM Param Store) after apply-time and read from at plan/before apply time.

Stores are pluggable and configurable and multiple may be enabled at the same time (i.e. for prod/non-prod, east/west, etc).

The initial set of stores we are implementing as part of this PR are:

AWS SSM Parameter Store

Summary by CodeRabbit

• New Features

  • Introduced a new Store interface with methods for storing and retrieving data.
  • Added support for AWS SSM Parameter Store and an in-memory store implementation.
  • New event hooks for Terraform operations, enhancing extensibility.
  • Enhanced CLI configuration with store management capabilities.
  • Added constants for Atmos YAML functions to improve maintainability.

• Bug Fixes

  • Improved error handling across various functions and methods.

• Documentation

  • Updated documentation to reflect new functionalities and configurations.

• Tests

  • Added unit tests for the new store implementations and their methods.