Mixed manifests provisional canvases and merging of manifests implementation

[JackLewis-digirati]

resolves #432
resolves #433
resolves #448
resolves #450

This PR modifies the provisional canvas paintings to work with the new mixed manifests feature.

Additionally, the manifest merger has been updated to provide final manifests that work with a mixture of items and painted resources

There has been a modification to settings to allow the settings based path generator to generate provisional paths, as opposed to the config generator. This has meant a reorganisation of settings and the api now implements the presentationApiUrl settings previously only available in the background handler.

An example of this new settings block now looks like this:

"PathSettings": {
    "PresentationApiUrl": "https://localhost:7230",
    "CustomerPresentationApiUrl": {
      "2": "https://dlcs-dev.example",
      "3": "https://dlcs-test.example"
    },
    "PathRules": {
      "Defaults": {
        "ResourcePublic": "/presentation/{hierarchyPath}",
        "ManifestPrivate": "/{customerId}/manifests/{resourceId}",
        "CollectionPrivate": "/{customerId}/collections/{resourceId}",
        "Canvas": "/{customerId}/canvases/{resourceId}"
      },
      "Overrides": {
        "example.com": {
          "ResourcePublic": "https://foo.com/{customerId}/{hierarchyPath}",
          "ManifestPrivate": "/{customerId}/manifests/{resourceId}",
          "CollectionPrivate": "/{customerId}/collections/{resourceId}",
          "Canvas": "/{customerId}/canvases/{resourceId}"
        }
      }
    }

Note

where these settings supersede settings with the same name in the previous iteration

Important

this PR will require changes to the terraform

Note

This PR also reverts changes from #290 which disallows manifests being created with either assets or items in the MVP

[donaldgray]

Couple of comments. I think items / item is overused in params and vars and more accurate naming might help clarify what's happening?

[donaldgray]

As discussed on call, couple of issues to resolve

• Invalid canvas.Id on matched Canvas results in the Canvas being ignored (extra slug - https://localhost:7230/presentation/7/canvases/asimov)
• Receiving "Error creating DLCS space" when there was a general DLCS error. This was related to attempting to delete null AssetId (maybe one for another ticket)?
• General comment - too much reliance on canvasOriginalId. We can accept different forms of CanvasId, which we reduce to the "id" part but we join on canvasOriginalId, which could result in us joining 2 different forms.
• Empty annotationPages ("items": []) in a matched canvas breaks handling (check .IsNullOrEmpty() rather than == null somewhere?)
• GenerateProvisionalCanvas() - if matched canvas then we should add provisional paintingAnnotation. Linked to above, don't use canvasOriginalId for matching.

[donaldgray]

LGTM - did some manual tests locally. Skimmed code due to size, couple of point raised but minor and mostly around comments.