Change keyword const to literal

[lars-reimann]

Is your feature request related to a problem?

const parameters accept only literals. const may imply that any expression that can be evaluated statically to a constant can be used.

Desired solution

Change the const keyword to literal.

Possible alternatives (optional)

We may support both const (must evaluate to a constant) and literal (must be literal) modifiers. The first one is a requirement for constraints. The second one is a requirement for the sidebar in the graphical editor.

Only one of these modifiers can be used on a parameter.

Screenshots (optional)

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Additional Context (optional)

No response