Add OpenFaaS OEM as a deployment option in the Helm chart

[welteki]

Description

Add Helm parameters to deploy OpenFaaS OEM:

openfaasOEM: true

faasnetesOEM:
  image: ghcr.io/openfaasltd/faas-netes-oem:0.1.0-rc1

Why is this needed?

• I have raised an issue to propose this change (required)

Add support for OpenFaaS OEM, a less restricted version of OpenFaaS CE.

Who is this for?

What company is this for? Are you listed in the ADOPTERS.md file?

How Has This Been Tested?

• Verified the chart works to deploy OpenFaaS OEM.
• Verified the chart still works for OpenFaaS Pro and OpenFaaS CE

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.