refactor: KnoraSipiIntegrationV2ITSpec simplifications (DEV-3504)

[siers]

Pull Request Checklist

Task Description/Number

Refactoring changes are split per commits whose descriptions are (time ascending order):

• reuse header adding code, reuse jsonLdHttpEntity
• add WithAsIs(asOpt) and create assertingUnique
• actually use jsonLdHttpEntity everywhere
• def requestJsonLdWithAuth(request) = request with "~> addAuthorization"
• reuse URLencode + getResponseJsonLD inlining
• flatten some UploadFileRequest.make().toJsonLd calls
• import OntologyConstants._ and the resulting changes
• moving around a few things (diff: +10, -41)

Issues in tests discovered while working on DEV-3504.

PR Type

• build/chore: maintenance tasks (no production code change)
• docs: documentation changes (no production code change)
• feat: represents new features
• fix: represents bug fixes
• perf: performance improvements
• refactor: represents production code refactoring
• test: adding or refactoring tests (no production code change)
• deprecated: Deprecation warning (ideally referencing a migration guide)

[linear]

DEV-3504 Add support for X-Asset-Ingested for FileValue creation and update

[siers]

I'll let the CI for int. tests run, then I'll push the formatting.

[siers]

Int. tests were green, pushed formatting.