Remove DepthWrappingVertex<T>

[smoogipoo]

This is a breaking change so I suggest applying it as late as possible as there will be other breaking changes.

Taking the opportunity to make a bit of a breaking change while cleaning this up. The existence of this object is a bit weird - it's as if it's an implementation detail yet is not treated as an implementation detail - you need to be very well aware that this is a thing when implementing renderers.

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vNext

TexturedVertex2D must be initialised with an IRenderer.

The default constructor for this type has been obsoleted and will now generate a compiler error.

[bdach]

Code looks quaint enough. Will run some platform testing later but I don't expect surprises.

[bdach]

TIL that this is legal C#.

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/expressions#12813-this-access:

When this is used in a primary_expression within an instance constructor of a struct, it is classified as a variable. The type of the variable is the instance type (§15.3.2) of the struct within which the usage occurs, and the variable represents the struct being constructed.

[peppy]

Might be legal, but I'd have no idea what this means nor how to quickly find the documentation for what it means 😅 . Might be worth a comment?

[bdach]

It's just a shorthand to initialise all members of the struct to default values for their type, as explicit initialisation is required for structs. Easier to write this = default; than to do this per member in both ctors.

Can agree with inline comment.

[bdach]

Inline comment added in 3da4187