[FEATURE] Command to generate XSD Schemas for ViewHelpers

[s2b]

This feature is a re-implementation of the XSD schema generator, which was previously
available as a separate package ¹. These schema files provide auto-complete in IDEs
(like PHPStorm) for all available ViewHelpers in a composer project.

The bin/fluid CLI command now supports the additional command schema, which scans
the whole composer projects for valid ViewHelper classes. The class in question needs
to meet the following requirements, which enforces already-existing conventions:

• file name must end with ViewHelper.php
• file path must contain a directory ViewHelpers, which serves as a divider between
  a Fluid namespace and its ViewHelpers
• class must implement ViewHelperInterface
• class name must end with ViewHelper
• class must not be abstract

These conditions are checked by ViewHelperMetadataFactory, which then creates the
corresponding ViewHelperMetadata value object. The SchemaGenerator then receives
a list of ViewHelperMetadata objects as well as an XML namespace (like
http://typo3.org/ns/TYPO3Fluid/Fluid/ViewHelpers) and generates an xsd schema file
that describes the ViewHelper and its arguments. The ConsoleRunner collects these files, creates unique file names and writes them as schema_*.xsd files to the destination
folder, specified with --destination.

IDEs either pick up those files automatically or need to be configured manually to
do so.

Footnotes

1. https://github.com/TYPO3/Fluid.SchemaGenerator/ ↩

[RozbehSharahi]

I am not through with the code-review yet. Nevertheless here already some comments. Hope it helps.

[RozbehSharahi]

🥳

[simonschaufi]

I'm unhappy with the implementation as it lacks the namespace parameter which exited before 😢

Before I had individual calls to generate the schema files for each extension individually of my project which doesn't work now anymore.

It also crashes for 3rd party extensions: #1005