sam publish supports publishing applications recursively

### Describe your idea/feature/enhancement

sam publish command currently only publish the template to SAR. But if the template has nested applications in it that is referenced to local templates, it does not publish the nested applications.

For example, I have the following two templates:

parent.template.yaml
```
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'

Metadata:
AWS::ServerlessRepo::Application:
Name: parent-application
Description: >-
This is my parent application.
Author: luhong
SpdxLicenseId: Apache-2.0
SemanticVersion: 0.1.1
LicenseUrl: LICENSE
ReadmeUrl: README.md

Resources:
NestedApp:
Type: 'AWS::Serverless::Application'
Properties:
Location: 'nested.template.yaml'
```

nested.template.yaml
```
AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'

Resources:
queue:
Type: 'AWS::SQS::Queue'
```

When I run `sam publish -t parent.template.yaml`, it should publish both parent.template.yaml and nested.template.yaml to SAR. In parent.template.yaml, the location should be changed to the applicationId and semanticVersion of nested.template.yaml app in SAR.