AWS::EC2::Availability Zone Opt in enablement

## Instructions for CloudFormation Coverage New Issues Template

Quick Sample Summary:
1. Title -> AWS::Service::Resource-Attribute-Existing Attribute
2. Scope of request -> AWS::Service::ResourceType::TheResource-ExistingAttribute supports A and B today, but not new C feature.
3. Expected behavior -> In Create, it should include this and this, like the console. Also include tag creation, like the API allows.
4. Test case recommendation (optional) -> it should help me do X given existing Y (if applicable); it should/shouldn't change Z.
5. Links to existing API doc (optional) -> Updated API docs at https://example.com/api-new.html
6. Category tag (optional) -> Compute
7. Any additional context (optional)

Detailed Instructions to create a new issue here: (delete this text before you save your issue, to keep them as short as possible :) ).

## 1. Title
In the format AWS::Service::Resource-Attribute-Existing Attribute)
Samples:
#### AWS::Service::NewResource
#### AWS::Service::ExistingResource-NewAttribute
#### AWS::Service::ExistingResource-ExistingAttribute-NewOption

We are hoping that the title makes it easy for others to scan it quickly in kanban board or issue list.

## 2. Scope of request
Enable Opting-In to AvailabilityZones like Local Zones and Wavelength Zones

aws ec2 modify-availability-zone-group \
--group-name us-west-2-lax-1 \
--opt-in-status opted-in

Start with the requested `aws ec2 modify-availability-zone-group` command and determine how opting in to Local Zones and Wavelength Zones should be represented in CloudFormation. Done means the relevant CloudFormation coverage supports this opt-in behavior, but the issue does not name a resource, file, or test to guide implementation.

Written by the indexing model from the issue text.