feat(builders): form schema, group and field builders

[kevinkosterr]

Summary

This pull request introduces a new way to create form schemas that are inspired by how Zod defines it's validation schemas. Essentially what this means is that instead of having to write JSON objects to define a schema, you can define a schema using builders.

The current way of defining a schema:

const form = ref({
 model: { ... },
 fields: [ ... ],
 groups: [ ... ]
})

A new way to define a schema would look something like:

import { f } from '@kevinkosterr/vue3-form-generator'

const schema = f.schema(
  { textModel: '', selectModel: '' } // Your regular model definition
  f.text('textFieldName', 'textModel').placeholder('This is a placeholder'),
  f.select('selectFieldName', 'selectModel').addOption('Test', 'test').multiple(false)
)

To define a field, and get it's JSON object you could do something like this:

import { f } from '@kevinkosterr/vue3-form-generator'

const selectFieldSchema = f.select('name', 'modelKey').addOption('Foo', 'foo').build()

Checklist

• The commits in this PR follow the commit guidelines
• The pull request was issued to the master branch (if not part of a release)

What kind of change(s) does this PR introduce? (Check at least one)

• Bug fix 🐛 - fix(...)
• Feature - feat(...)
• Documentation - docs(...)
• Introduces or modifies test(s) - test(...)
• Other (please describe)