One-click deployment CloudFormation template support

I want to publish CDK application to CloudFormation template with assets to S3 with one-click deployment enabled.

### Use Case

There still are some barriers for end users to apply/evaluate a CDK based solution(installing prerequisites tools, cloning AWS solution source, installing dependencies, configuring aws credential, finally deploying cdk application).

One-click deployment CloudFormation template would simplify the user experiences.

Currently the synthesized output CFN template is using `CfnParameter` for external assets that will be specified in deployment runtime. It's very difficult to fill those parameters properly with the assets information in a manual publishing.

### Proposed Solution

I think the most of work already done in `cdk deploy` command, it always uploads assets and templates to cdk staging bucket, then create cloudformation stack with parameter values of assets from previous step.

The cdk tool impments a new command `publish` to publish the assets to S3 bucket then updated template with default values for asset parameters and publishing it to S3 bucket as well.

The `publish` command can specify s3 bucket with prefix for publishing the artifacts or use the cdk-staging-bucket as default bucket.

### Other

* [ ] :wave: I may be able to implement this feature request
* [ ] :warning: This feature might incur a breaking change

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This is a :rocket: Feature Request

Start by tracing the existing cdk deploy asset-upload and CloudFormation stack parameter flow described in the issue. Define how a proposed publish command would accept an S3 bucket and prefix, upload assets, replace asset parameter defaults, and publish the resulting template. Done means the generated template and assets support one-click CloudFormation deployment.

Written by the indexing model from the issue text.