Add testproperty back to the Object and Field Picklist for backwards compatibility

[StreckerCM]

Removing testproperty from the field broke backwards compatibility and prevents upgrading the package. The property cannot be removed since isExposed is true for this LWC.

To resolve testproperty will need to be added back to the LWC.

https://developer.salesforce.com/docs/platform/lwc/guide/use-packaging-add.html

[StreckerCM]

@jdayment @alexed1 @ericrsmith35 I created the pull request #1588 to patch the upgrade issue reported by @philryan29

[chris-smr]

Please approve and merge #1588 ASAP.

Request simply adds back 'testproperty' property that was removed from fsc_pickObjectAndField3, no actual code is changed. Until 'testproperty' is added back, anyone attempting to update FlowBasePackComponents from an older release to the latest will encounter this error:

fsc_pickObjectAndField3 can’t remove the following public properties: testproperty, because the component is part of a managed package