Find and replace all magic number node parameter indexes with ::INDEX const

This issue must be completed WITHOUT ANY AI USAGE. It does not involve writing code, just searching through lots of code diligently and without missing important details. This is something AI is not able to be trusted for.

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The task here is to use various searching and go-to-references/implementations techniques to find as many magic number indexes as possible for node parameters, and replace them with their node parameter's ::INDEX constant.

For example, two parameters of the Stroke node:

• graphene_std::vector::stroke::ColorInput::INDEX (equals 1)
• graphene_std::vector::stroke::DashLengthsInput::<Vec<f64>>::INDEX (equals 8)

Since this ::INDEX system is newer, there are many places we have magic numbers for indexes like 1 and 8 lying around in the code. They are probably often used to generate values for specific function calls. For example, InputConnector::node is one such function that can have its usages searched to find plenty of examples where magic number indexes are passed in, that should be replaced by an ::INDEX const instead. In some cases, this could be indirect, like if that function is passed a variable set elsewhere. And there are likely other functions besides that one, too, that are receiving magic number indexes.

After those techniques are completed, a final check should be done by manually checking through the ~1.5k (perhaps less after the other replacements are completed) results from this project-wide search:

• Enable regex but not word boundaries or capitalization
• Query: (?<!\d|[a-z]|\.|\\|'|"|= ?|> |return |[-+/*%] ?|_|; |NodeId\(|box\[|bounds\[|points\[|points_viewport\[|locations\[|display_decimal_places\(|_vertical\[|_horizontal\[|segments\[|handles\[|corners\[|radii\[|default\(|\.skip\(|\.min\(|\.max\(|digit: |Step |Case |Test |", |Vec2::new\(|powi\(|\[\d\]\[|\.0\[|[\s(][a-z]\[)[1-3]?\d(?!\d|[a-z]|\.|'|"|_|;.| [<>=]| ?px|\]\[|\]\.)
• Files to include: editor/**/*.rs, node-graph/**/*.rs
• Files to exclude: document_migration.rs, document_node_definitions.rs