feat: Storage size settings for AMI builder

[kichik]

const builder = Ec2RunnerProvider.imageBuilder(stack, 'AMI Linux Builder', {
  awsImageBuilderOptions: {
    storageSize: cdk.Size.gibibytes(33),
  },
});
const provider = new Ec2RunnerProvider(stack, 'Linux Provider', {
  labels: ['big-linux'],
  imageBuilder: builder,
});
new GitHubRunners(stack, 'Runners', {
  providers: [provider],
});