aws-ec2: support subnet group names on fromVpcAttributes

### Describe the feature

When importing a VPC I'd like to support names for subnets.

### Use Case

When multiple subnet groups for one network type (for example ISOLATED) exist I want to select a certain group using subnet selection.

### Proposed Solution

extend fromVpcAttributes -> VpcAttributes so an import can look like this:

```typescript
Vpc.fromVpcAttributes(this, 'Vpc', {
vpcId: 'vpc-id',
isolatedSubnetNames: [
{ subnetGroupName: 'Database', subnetId: 'subnet-database-1' },
{ subnetGroupName: 'Database', subnetId: 'subnet-database-2' },
{ subnetGroupName: 'App', subnetId: 'subnet-app-1' },
{ subnetGroupName: 'App', subnetId: 'subnet-app-2' },
],
});
```

### Other Information

Right now it's only possible to import up to 3 different subnet groups, however there are instances where I want to have more subnet groups.

### Acknowledgements

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

### CDK version used

2.163.1

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

-

Start at Vpc.fromVpcAttributes and the VpcAttributes definition, then trace how imported subnet groups are represented and selected. Determine how named subnet groups should coexist with the current limit of three groups. Done means an imported VPC can accept the proposed isolatedSubnetNames shape and select subnets by subnetGroupName without breaking existing imports.

Written by the indexing model from the issue text.