Add flat label list tab

[lehecht]

• Add tests in VideoAnnotationControllerTest
• Add tests in ImageAnnotationControllerTest
• Add project largo flat tab view
• Update annotation count after swapping/deleting labels
• Update label highlighting in LabelTab (and vice versa)

Closes #170.

[mzur]

Looks really nice! Here come the high-level comments:

• If I read the code right, you populate the tab based on a list of all annotations in the project/volume? This is far too inefficient. Instead, the API should return a list of labels only (and their number of annotations), i.e. exactly what the tab should show. You should be able to get this list with a single DB query, too. Then there also should be no need for a streamed response.

• The labels should be ordered alphabetically (like with the trees).

• The new tab should be the second from the top.

• The new tab title should be "label list".

• There is an issue with the spacing of selected labels:

  Screencast.from.06.12.2024.11.58.27.webm

[lehecht]

@mzur

• the API should return a list of labels only (and their number of annotations)

If I return only the labels, it is not possible any more to use them later for the labels tree tab, because it needs the image's uuid and annotation id.

[mzur]

But the labels for the label trees tab already come from biigle.$require('largo.labelTrees'), right? The new API endpoint is only there for the new flat labels tab so the endpoint can only return the information required for this tab, too.