[Import] [Test] Initial test on loadSavedMapping function.

[eileenmcnaughton]

Overview

Adds a test - minor changes to support it

Before

No test

After

Minimal testing - more to come

Technical Details

To facilitate this I
1) made it public - in the end it will go anyway
2) removed a 'pass-through' variable from the return array - it is passed in & returned unchanged
3) made it cope without a notice when a class property is not defined - that will go too soon

Comments

Will rebase if #15049 is merged first

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).

[eileenmcnaughton]

@seamuslee001 I rebased this now you merged the other

[seamuslee001]

Looks fine adding Merge on Pass

[seamuslee001]

Jenkins re test this please