[Git Sync] - [Enhancement] - support samconfig or increase feature parity between "stack deployment file" and samconfig, and otherwise configuring Git sync via IaC

### Name of the resource

Other

### Resource name

CloudFormation Git sync

### Description

The [recent feature](https://github.com/aws-cloudformation/cloudformation-coverage-roadmap/issues/1875#issuecomment-2364251475) announced by @gotamp and @kohidave brings Git sync closer to something we might use in our org.

I realize this is a relatively young feature, and that you probably have many yet-to-be-realized plans for it. Hopefully the below is useful to hear, in terms of how the feature could be made more useful for at least one org.

# samconfig support or feature parity

I'm particularly interested in how Git sync introduces the "stack deployment file" into the CFN ecosystem. We're presently using sam and [its samconfig file](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-config.html) to specify stack configuration.

It would be useful if Git sync either supported `samconfig` directly, or increased feature parity between the "stack deployment file" and `samconfig`. The [docs for each sam cli command](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-command-reference.html) list supported flags - each specifiable in `samconfig` (dashes in flags replaced by underscores when specified via `samconfig`).

A particularly useful config supported via `samconfig` and seemingly not yet supported via "stack deployment file" is `role_arn` - described in the [sam deploy documentation](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-cli-command-reference-sam-deploy.html) like so ...

> The Amazon Resource Name (ARN) of an IAM role that AWS CloudFormation assumes when applying the changeset.

In addition to the many flags specifiable via `samconfig`, it's also handy that multiple stacks can be specified in a single `samconfig` file, and that `stack_name` can be included in the source controlled file.

# managing Git sync config via IaC

Speaking of source controlled files, is there any current or planned method for configuring Git sync via file - for example, by introducing new CFN resource types? It seems a little odd that a feature of an IaC service can only be configured via console. The `AWS::CloudFormation::*` namespace seems like a good home for one or more `GitSync*` resource types.

### Other Details

_No response_