Params prefix in Knot.x Forms.

**Is your feature request related to a problem? Please describe.**
Knot.x snippet prefix parameters are configurable. We can set this prefix as empty string. Then the snippet markup will look like:

```

```

instead of

```

```

The same option should be available for forms parameters.

**Describe the solution you'd like**
```

Start by locating the forms parameter configuration and the code that renders form markup, then compare it with the existing configurable snippet prefix behavior. Done means the same prefix option can produce form attributes without the default prefix, with coverage for the empty-prefix example shown in the issue.

Written by the indexing model from the issue text.