feat: add multi-org generate_params.py (#672)

## Why?

When running ADF in a multi-org setup, this feature allows you to set stage-specific files in the repositories' `params` folder. This feature doesn't break existing parameter generation. It just adds a new feature.

## Example

Let's assume that we have a three AWS Org setup with a dev, int and prod AWS Org. 
That implies that the SSM param "/adf/org/stage" will have one of the following values: [dev, int, prod]. For now, let's assume the value is set to "dev".
Let's further assume that, the `params` folder of our target repository has the following structure:

- params:
   - global_dev.yml
   - global_int.yml
   - global_prod.yml
   - global.yml

With this feature, the param file global_dev.yml will be selected based on the value "dev" in SSM param "/adf/org/stage".

---------

Co-authored-by: Andreas Falkenberg
Co-authored-by: Simon Kok

docs/user-guide.md

@@ -648,11 +648,12 @@ the corresponding OU parameter file will not be referenced.
 
 ```txt
 global.yml
-└───deployment_account_region.yml (e.g. global_eu-west-1.yml)
-    └───ou.yml (e.g. ou-1a2b-3c4d5e.yml)
-        └───ou_region.yml (e.g. ou-1a2b-3c4d5e_eu-west-1.yml)
-            └───account.yml (e.g. dev-account-1.yml)
-                └───account_region.yml (e.g. dev-account-1_eu-west-1.yml)
+└───deployment_org_stage.yml (e.g. global_dev.yml)
+  └───deployment_account_region.yml (e.g. global_eu-west-1.yml)
+      └───ou.yml (e.g. ou-1a2b-3c4d5e.yml)
+          └───ou_region.yml (e.g. ou-1a2b-3c4d5e_eu-west-1.yml)
+              └───account.yml (e.g. dev-account-1.yml)
+                  └───account_region.yml (e.g. dev-account-1_eu-west-1.yml)
 ```
 
 This concept also works for applying **Tags** to the resources within your
@@ -712,6 +713,31 @@ the root of the repository.
 *Note:* Currently only Strings type values are supported as parameters to
 CloudFormation templates when deploying via AWS CodePipeline.
 
+#### CloudFormation Parameters in a Multi-Organization ADF Setup
+
+The CloudFormation Parameter generation feature is fully compatible with
+the [Multi-Organization ADF Setup](./multi-organization-guide.md) approach.
+
+For example, in a setup with three AWS Organizations; with a separate
+`dev`, an `int`, and a `prod` AWS Organization. This implies that the
+SSM parameter `/adf/org/stage` will have one of the following three
+values: `dev`, `int`, or `prod`; depending on the AWS organization
+you are in. Let's further assume that your application in scope
+requires AWS Organization specific parameters. In that case,
+the `params` folder should  have the following content:
+
+```txt
+params
+└───global_dev.yml
+└───global_int.yml
+└───global_prod.yml
+└───global.yml
+```
+
+Where it will prefer the AWS Organization specific configuration
+`global_${org_stage}` over the `global` parameters in case they both
+match the same parameter or tag.
+
 ### Serverless Transforms
 
 If the template that is being deployed contains a transform, such as a

src/lambda_codebase/initial_commit/bootstrap_repository/adf-build/shared/generate_params.py

@@ -118,6 +118,7 @@ class PipelineDefinition(TypedDict):
 DEPLOYMENT_ACCOUNT_REGION = os.environ["AWS_REGION"]
 PROJECT_NAME = os.environ["ADF_PROJECT_NAME"]
 EMPTY_PARAMS_DICT: ParametersAndTags = {'Parameters': {}, 'Tags': {}}
+ADF_ORG_STAGE = os.getenv("ADF_ORG_STAGE", "dev")
 
 
 class Parameters:
@@ -229,6 +230,7 @@ def create_parameter_files(self) -> None:
                 i.e. "/devsecops/security_eu-west-1"
             1. f"{organization_unit_path}" i.e. "/devsecops/security"
             1. f"{global}_{region}" i.e. "global_eu-west-1"
+            1. f"{global}_{stage}" i.e. "global_dev"
             1. f"{global}" i.e. "global"
 
         It will then generate a JSON file that holds all the parameters per
@@ -299,6 +301,14 @@ def create_parameter_files(self) -> None:
                     ),
                     current_params
                 )
+                # Compare account_region final to global_stage
+                current_params = self._merge_params(
+                    Parameters._parse(
+                        params_root_path=self.cwd,
+                        params_filename=f"global_{ADF_ORG_STAGE}",
+                    ),
+                    current_params,
+                )
                 # Compare account_region final to global
                 current_params = self._merge_params(
                     Parameters._parse(