REST API to create workspaces from a devfile

Description

Currently there is a way to create a workspace from a devfile https://github.com/eclipse/che/blob/master/wsmaster/che-core-api-devfile/src/main/java/org/eclipse/che/api/devfile/server/DevfileService.java#L98-L116

We can post a devfile content.

I would like to be able to create workspaces from content like this one: https://github.com/redhat-developer/devfile/blob/master/Devfile.yaml

Let say I’m a client like the dashboard where I could create content of such devfile, then this devfile is referencing other files by doing something like: local: petclinic.yaml

How could I submit such files through REST API ?

would it be something like MULTIPART_FORM_DATA / https://github.com/codenvy-legacy/che-core/blob/3.x/platform-api/che-core-api-factory/src/main/java/org/eclipse/che/api/factory/FactoryService.java#L166

or to submit content with a all-in-one format

---BEGIN DEVFILE---
content
---END DEVFILE---
---BEGIN petclinic.yaml---
content
---END petclinic.yaml---

something else ?

somehow related to https://github.com/eclipse/che/issues/11549

[sleshchenko]

I’m OK with

local: petclinic.yaml
localContent:  | 
<file content here>

[garagatyi]

This would be reflected in the JSON Schema of devfile. Let’s consult with authors of the JSON Schema @l0rd @mshaposhnik @sleshchenko @skabashnyuk WDYT guys about the changes suggested by Florent? If you are OK with them I’ll work on it