Add support for file download

[kumarvishal]

Description

• Add support for downloading a file saved in 'upload' folder at instace

We've an API available in backed named downloadFile.jsp which provides us a way to download the file from instance server.

This API is complmentry of uploadFile.jsp which we're using in ACC WebUI to upload files for various puposes. These files go to 'upload' folder on the instance's home folder and we can download only those file which are available in this folder.

We already have a fileUploader.upload available in this SDK, adding support for fileUploader.download in this PR.

It is important to keep this under fileUploader because this is not a generic utility and can download files only from upload folder i.e. can only download the files which are uploaded using fileUploader.upload.

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] I have signed the Adobe Open Source CLA.
• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[kumarvishal]

Hi Vishal, this looks good. There are a few minor details, could you please make the changes?

Hi Alex

Thanks for review, I’ve update the PR #106 with requested changes.

Please re-review.