Data Warehouse: Support for multiple external access KNPs

#### Description:

Right now the chart only support one KNP in its `external-access: ` values.
We can make it so that we support multiple through a Yaml array (and fix the capitalization)

```yaml
externalAccess:
- instanceName: ~
environment: ~
prefix: ~
- ...
```
- [ ] the KNP file needs to iterate over that array
- [ ] and of course a commented out example in the sample values file

#### Acceptance Criteria:

Given
When
Then

#### Development Checklist:

- [ ] Checklist item
- [ ] Checklist item
- [ ] Checklist item
- [ ] Meets the DOD

#### Definition of Ready (Note: If any of these points are not applicable, mark N/A)

- [ ] User story is included
- [ ] User role and type are identified
- [ ] Acceptance criteria are included
- [ ] Wireframes are included (if required)
- [ ] Design / Solution is accepted by Product Owner
- [ ] Dependencies are identified (technical, business, regulatory/policy)
- [ ] Story has been estimated (under 13 pts)

#### Definition of Done (Note: If any of these points are not applicable, mark N/A)

- [ ] Acceptance criteria are tested by the CI pipeline
- [ ] UI meets accessibility requirements
- [ ] Configuration changes are documented, documentation and designs are updated
- [ ] Passes code peer-review
- [ ] Passes QA of Acceptance Criteria with verification in Dev and Test
- [ ] Ticket is ready to be merged to main branch
- [ ] Can be demoed in Sprint Review
- [ ] Bugs or future work cards are identified and created
- [ ] Reviewed and approved by Product Owner

#### Blocked By/Blocking

#### Notes:

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