docs: Upload and view a document

[jeromecambon]

Covers BPM-320

[github-actions]

📝 Contribution Summary

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The following pages were updated, please ensure that the display is correct:

• applications/ui-builder/how-to-handle-document
• applications/ui-builder/how-tos-builder

[github-actions]

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Filename	Before	After	Improvement	Visual comparison
modules/applications/assets/images/ui-builder/guides/file-picker-setting.png	75.43 KB	40.00 KB	-47.0%	View diff

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[AleRondon]

Can we please add an example on how to use the file viewer for a document with the information provided by the task context?

[marcobonita]

Typos and rephrasing

[jeromecambon]

Can we please add an example on how to use the file viewer for a document with the information provided by the task context?

I succeeded to upload the document as base64, access it via a Bonita task, and view it in the DocumentViewer widget. However, the document is not viewable by UID widget (in the admin app for example), which requires a binary format.
I didn't succeed to upload the document as binary, and encode it as base64 to make it readable by the widget. I encoded as base64, but I still have a blank result on the widget...
I propose to merge this PR, since it add some interesting values. We can handle the issue separately.