Generate a feature file from a parsed document

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

As one has the Parser like here:
```
parser = Parser()
gherkin_document = parser.parse("Feature: ...")
```
and has changed/updated a few elements of the gherkin_document (which is really just a dictionary in Python)
Isn't it logical for many instances to want to re-generate the feature file ?

### ✨ What's your proposed solution?
A script which extracts the information from within the Parsed Gherkin document and generates a valid .feature file with this feature

### ⛏ Have you considered any alternatives or workarounds?
If there is not none already the only way to go is to build one myself but for this community it would be a more mature solution if you could integrate it in this repo

### 📚 Any additional context?

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Start with the Parser.parse example and inspect how the returned gherkin_document is represented and exposed by the API. Define the supported document elements and serialization rules before locating an implementation entry point. Done means modified parsed documents can be generated as valid .feature text, with coverage for the supported cases.

Written by the indexing model from the issue text.