Orchestrator should ignore packageDirectories without a "package" attribute

[rody]

Orchestrator requires all packageDirectories in the sfdx-project.json to be declared as packages (i.e. it requires package and versionNumber attributes).

Salesforce DX allows to declare directories that are not packages. This is quite useful when you want to have a specific path for the metadata that you pull from a Scratch Org.

To Reproduce
Add the following to the packageDirectories in sfdx-project.json:

{
  "path": "tmp",
  "default": true
}

and run sfdx sfpowerscripts:orchestrator:build

It results in the following error

ERROR running sfpowerscripts:orchestrator:build:  The sfdx-project.json is invalid, Please fix the following errors

1: /packageDirectories/2: must have required property 'package' {
    "missingProperty": "package"
}
2: /packageDirectories/2: must have required property 'versionNumber' {
    "missingProperty": "versionNumber"

Expected behavior
The tmp packageDirectory is ignored from the list of packages to create (because it does not have a package or versionNumber attribute). The other packages are built.
Optionally a info message could be displayed saying that the directory is ignored because it's not a package.

Implementation note: If package is present but not versionNumber (and vice-versa), then sfpowerscripts should fail with an error message, since the package definition is incomplete.

[azlam-abdulsalam]

Thanks @rody for raising this. Will try to add this as part of April's release