Allow preconfigure in schema

[1000TurquoisePogs]

When schema was introduced to zowe (v2.4?) the script stage "preconfigure" was never added.
It seems uncommon, so nobody noticed for a long while, but we do still have a need for it.
I checked the code and it seems code to handle it still exists, but the omission from the schema was gating its use.

[github-actions]

build 6298 SUCCEEDED.
Link to workflow run: https://github.com/zowe/zowe-install-packaging/actions/runs/11390853684

[github-actions]

build 6299 SUCCEEDED.
Link to workflow run: https://github.com/zowe/zowe-install-packaging/actions/runs/11390863269

[github-actions]

Test workflow 5610 is started.
Running install test: Convenience Pax
The zowe artifact being used by this test workflow: libs-snapshot-local/org/zowe/3.1.0-PR-4055/zowe-3.1.0-pr-4055-6299-20241017183515.pax
Running on machine: zzow08
Result: FAILURE
Link to workflow run: https://github.com/zowe/zowe-install-packaging/actions/runs/11390963528

[github-actions]

Test workflow 5609 is started.
Running install test: Convenience Pax
The zowe artifact being used by this test workflow: libs-snapshot-local/org/zowe/3.1.0-PR-4055/zowe-3.1.0-pr-4055-6298-20241017183456.pax
Running on machine: zzow06
Result: FAILURE
Link to workflow run: https://github.com/zowe/zowe-install-packaging/actions/runs/11390959812