Reference variables in parameter type regular expressions

### 🤔 What's the problem you're trying to solve?

We have some large parameter-types which we would like to use both in `*.feature` files and also in our typescript code. Small example how we have to do it currently (some of our types are much, much larger):

```typescript
defineParameterType({
name: 'MyType',
regexp: /"(Value1|Value2|Value3)"/,
transformer: (s) => s,
});

type MyType = 'Value1' | 'Value2' | 'Value3';
```
As you can see, we need to duplicate all type values.

### ✨ What's your proposed solution?

We tried a solution like this:

```typescript
const typeValues = [ 'Value1', 'Value2', 'Value3' ];

defineParameterType({
name: 'MyType',
regexp: new RegExp(`"(${typeValues.join('|')})"`),
transformer: (s) => s,
});

type MyType = Exclude;
```
Here the values are only defined once in `typeValues` without needing to repeat them. The CucumberJS runner also runs the scenario fine. But, the VSCode extension does not recognize the step anymore and marks it as not existing.

Is it possible that `defineParameterType()` can accept a variable for the `regexp` parameter?
### ⛏ Have you considered any alternatives or workarounds?
-

### 📚 Any additional context?
-

Start at the VSCode extension's handling of defineParameterType() and compare how it recognizes a literal regexp with a regexp constructed from a variable. Done means parameter types whose regexp is built from shared TypeScript values are recognized by the extension without duplicating the values.

Written by the indexing model from the issue text.