aws-cdk-lib: Improved Experience for working within context of AWS Organization

### Describe the feature

I wanted to open a thread for discussion on ecosystem ideas for improving the experience with working within the context of an AWS Organization as the product reaches maturity for resource sharing / account sharing / cross-account access etc.

An example of what I mean is for grantables / iam permissions, a very nice feature on L2's would be something like a `grantOrg` method. I think it goes much deeper than that but that's the general idea. This isn't about L2's for AWS Org resources, but for interacting and managing AWS accounts and resources at a rudimentary level of the framework that exist within the context of an Org / Org Unit. Organizations has added a ton of functionality on access controls over the last couple years that could be built into the cdk w/ convenience methods

### Use Case

Improved experience for building AWS infra within context of a large organization

### Proposed Solution

Issue is more for for a broader discussion of what type of utilities for interacting with an Org should be added to low level base classes in cdk

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.167.0

### Environment details (OS name and version, etc.)

MacOS

Start by reviewing the proposed `grantOrg` method for L2 grantables/IAM permissions and the broader AWS Organizations use cases described in the issue. Define which account-sharing, resource-sharing, or cross-account access utilities belong in low-level CDK base classes, then document a concrete, scoped proposal and its completion criteria.

Written by the indexing model from the issue text.