Specify the source mapping path for component containers

[l0rd]

Currently, project source is mounted to either CHE_PROJECT_ROOT or /projects when mountSources is true. The CHE_PROJECT_ROOT value is configurable during Che setup via the che.properties file

If odo is to consume the devfiles, we would like it to have an alternate way to set the source path value in the component container, rather than having a fixed single value via either CHE_PROJECT_ROOT or /projects for all the devfiles.

This can be achieved by having sourceMapping when mountSources is true, which transfers/mounts the project to the specified path in the container.

Che can also use the property i.e.; when sourceMapping is present, it overrides the CHE_PROJECT_ROOT value if present and mounts the source to the path defined by sourceMapping

Example:

---
components:
  - container:
      image: "busybox"
      name: "mycontainer"
      mountSources: true
      sourceMapping: "/home/src"

[l0rd]

cc @johnmcollier @elsony

[l0rd]

Proposal reviewed and approved.

[kadel]

A small addition to this. The env variable should NOT be called CHE_PROJECT_ROOT anymore.
Something more generic would be better. Maybe just PROJECTS_ROOT