feat: Exportable public certificates

[magreenbaum]

Description

Support exportable public certificates.

Motivation and Context

• [Enhancement] aws_acm_certificate: support to issue an exportable certificate hashicorp/terraform-provider-aws#43207
• https://aws.amazon.com/about-aws/whats-new/2025/06/aws-certificate-manager-public-certificates-use-anywhere/
• Resolves AWS Public Certs Marked as Exportable #159

Breaking Changes

No.

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

[guillaumelecerf]

This commit breaks backward compatibility, thus one of the commit messages must have contained a ! to bump the major version, as it changes the required provider version.
@bryantbiggs : could you plz fix that?

[bryantbiggs]

how does this break backwards compatibility?

[github-actions]

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