Add organizational support for cloud-bench

[nkraemer-sysdig]

Now that hashicorp/terraform-provider-aws#21193 has been merged, this PR adds support for organizational cloud-bench onboarding. This PR was tested against out test org, and successfully onboarded & ran benchmarks in all member accounts.

Changes:

• Remove the account_id variable from the cloud_bench module. It is not needed, as we can use the aws_caller_identity inside the module to figure this out. This simplifies the examples.
• Bump minimum aws provider version
• Uncomment cloud-bench in the organization example
• Refactor cloud-bench module to do one of two things depending on is_organizational (using count and for_each):
  a) is_organizational = false - Pre-existing single-account implementation: Provisions a role/policy directly
  b) is_organizational = true - Fetches the list of member accounts, onboards each in our BE, creates benchmark task spanning all accounts, and uses a CFT StackSet in the management account to provision the required role/policies in each member account.

Notable features/behaviour:

• If is_organizational is set to true, but the user is not authenticated into an organizational management account, the stack fails with:

│ Error: Iteration over null value
│ 
│   on ../../modules/services/cloud-bench/main.tf line 15, in locals:
│   15:   member_account_ids = var.is_organizational ? toset([for a in data.aws_organizations_organization.org.non_master_accounts : a.id]) : toset([])
│     ├────────────────
│     │ data.aws_organizations_organization.org.non_master_accounts is null
│ 
│ A null value cannot be used as the collection in a 'for' expression.

• If a new member account is added/removed to the org, the role will be automatically created/removed. The Sysdig BE will not be updated however, so we may want to remove/rethink this setting

[wideawakening]

LGTM, can merge it @nkraemer-sysdig

• fixed pre-commit tf-docs

couple of non-blocking maintenance things though

• could you update the org diagram to reflect the changes?
• remove the "Note: CSPM/Compliance through cloud-bench module is not supported yet" note on the org README

[nkraemer-sysdig]

@wideawakening 6c3726e