Enhanced Input Expression Evaluation Control in Elsa Studio

- Similar to what we can do in custom activities, we need to expose the `AutoEvaluate` input property to the Studio so that you can define workflow inputs with that setting, which then instructs the engine to **not** auto-evaluate the input expressions (the default is to auto-evaluate all input expressions).
- We need a JS/Liquid/C#/Python function to let you evaluate input expressions from the designer, and/or provide an activity called e.g. `EvaluateExpression` that let's you do this and provides the result as its output.

_Originally posted by @sfmskywalker in https://github.com/elsa-workflows/elsa-core/discussions/4169#discussioncomment-7460999_