[REFACTOR] Enable the EWCCLI to parse `values` metadata

Hey @pacospace,

This is a change that slipts off from the metadata schema changes introduced as part of https://github.com/ewcloud/ewc-community-hub/pull/58 (additional details can be found as part of [PR review comments](https://github.com/ewcloud/ewc-community-hub/pull/58/changes#r2745182617) )

Specifically, what is needed is that EWCCLI is able to parse the newly introduced attributes under the `values` key, so that we can deprecate redundant attributes under the `ewccli` key.

Below is a complete list metadata attributes that are redundant, followed by their new name:

* `ewccli.inputs` -> `values.inputSpec`
* `ewccli.outputs` -> `values.outputSpec`
* `ewccli.pathToRequirementsFile` -> `values.pathToRequirementsFile`
* `ewccli.pathToMainFile` -> `values.pathToMainFile`
* `ewccli.defaultImageName` -> `values.osImageName`