Jenkins or GitHub Workflow: Update Submodules

As a: developer, I would like to adapt an existing, but unused GitHub workflow to work through Jenkins to automatically update submodules on push.

The existing workflow relies on a personal access token as described in the readme of the [repository](https://github.com/ISISComputingGroup/Update_Submodule_Workflow_Action) and the [wiki page](https://github.com/ISISComputingGroup/ibex_developers_manual/wiki/Shared-utility-scripts#github-workflows) which will need to be altered for use with submodules of the [EPICS parent repository](https://github.com/ISISComputingGroup/EPICS). - A personal access token should be avoided if tied to a specific user and not a GitHub organisation account.

If you need a hand understanding the workflow, feel free to contact [Jack Allen](https://github.com/JackEAllen)

### Acceptance Criteria
_What is the acceptance criteria?_
- [ ] A Jenkins workflow exists to replicate the [GitHub workflow](https://github.com/ISISComputingGroup/Update_Submodule_Workflow_Action)
- [ ] The Wiki is updated appropriately to describe new workflow [HERE](https://github.com/ISISComputingGroup/ibex_developers_manual/wiki/Shared-utility-scripts#github-workflows)

### Extra Information
_Why it is needed?_
- To remove the need for a check to take place asking a developer to perform this task manually.
- To optimise developer workflow.

_Where required files/links are_
- GitHub Workflow to use as base to work from: [Update Submodule GitHub Template Repository](https://github.com/ISISComputingGroup/Update_Submodule_Workflow_Action)
- Wiki Page describing workflow: [Workflows](https://github.com/ISISComputingGroup/ibex_developers_manual/wiki/Shared-utility-scripts)

## How to Test
_verbose instructions for reviewer to test changes
(**Add before making a PR**)_
1. Create a test parent repository and child repository and connect to workflow.
2. Make a change to the child repo see if change updated in parent repo on push to master / main branch.

Beginne mit der Prüfung des Repositorys Update_Submodule_Workflow_Action und der Wiki-Seite Shared-utility-scripts und vergleiche anschließend den bestehenden Workflow mit den Submodulen des übergeordneten EPICS-Repositorys. Lege den Jenkins-Workflow und den Ansatz für die Zugangsdaten fest, ohne auf ein persönliches Benutzer-Token angewiesen zu sein. Als erledigt gilt die Aufgabe, wenn der Workflow die Submodule bei Pushes in Child-Repositories aktualisiert und die Wiki-Seite dies dokumentiert; teste dies mit den angegebenen Parent- und Child-Repositories.

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