Add a new shader specifically for node sockets rather than using the
keyframe shader.
Motivation:
1. Allow easier addition of new socket shapes
2. Simplify socket drawing by avoiding special handling of multi-inputs
3. Support multi-inputs for all socket types (diamond, square, etc.)
The new shader is tweaked to look the same to the old ones.
**Comparison**
The biggest difference is that the multi socket is now more consistent
with the other sockets.
For single sockets there can be small size differences depending on zoom
level because the old socket shader always aligned the sockets to the
pixel grid. This could cause a bit of jiggling compared to the rest of
the node when slowly zooming. Therefore I left it out of the new shader
and it now scales strictly linear with the view.
**Multi Socket Types**
While there currently is no need for (.) internally, there are a few
obvious use-cases for multi-input field (diamond) sockets like
generalized math nodes with an arbitrary number of inputs (Add,
Multiply, Minimum etc.).
Co-authored-by: Jacques Lucke <jacques@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/119243
13e0077c5c