Custom view data model

[hahn-kev]

We want custom views to be synced between users, here's the model:

public class CustomView
{
    public Guid Id { get; init; }
    public required string Name { get; set; }
    public DateTimeOffset? DefaultAsOf { get; set; }
    public string? DefaultFilter { get; set; }
    public required string[] Fields { get; set; }
    public required WritingSystemId[] Vernacular { get; set; }
    public required WritingSystemId[] Analysis { get; set; }
    public ViewBase Base { get; set; }
}

public enum ViewBase
{
    FwLite,
    FieldWorks,
}

the view base will determine the field labels which are used. The field order is determined by the order they show up in the Fields list, that list can include custom fields by CustomFieldId (see #1966). Custom views will not support per field writing system visibility, if that is desired then that would fit better with tasks.

The change for this can be fairly simple just using either a json patch change, or a change which is created based on the custom view and just modifies the view in the Apply method, views won't change frequently and so conflicts will be rare.

This model is designed to have a single default Custom View (based on Max(DefaultAsOf)), we may want to have a default per user role (only manager, editor, observer exist right now), in which case we could have a separate table to track that or just list the roles that this CustomView is default for on a property.

[myieye]

If Fields were an array of objects, they'd be more flexible. E.g. some could be marked readonly.
I'm pretty sure we've heard of interest in read-only fields. If we want to avoid handling that via field-level permissions, then we could potentially handle it here directly in the view config.

[myieye]

We'll presumably keep our current behaviour of locally persisting the currently selected view, right? I.e. as a new user I get the default view, but if I pick a different view then FWLite will remember that the next time I open it.