Zelos does not support input outlines around filled inputs - causes preview weirdness

[BeksOmega]

Describe the bug

Zelos does not allow you to trigger an input outline around an input that has been filled.

This means that Blockly.zelos.Renderer.prototype.getConnectionPreviewMethod has to return a logically incorrect value (REPLACMENT_FADE) to get the desired behavior.

This only works because the replacement fade appears the same as an input outline (in zelos specifically). If they ever stop being the same, this will break.

Expected behavior

Zelos should support input outlines around filled inputs. This way the Blockly.zelos.Renderer.prototype.getConnectionPreviewMethod could return the correct value.

Additional context

I think all of the above information is correct, but I'm not super familiar with zelos so I could be wrong.

TODO link