Fix parsing of component tags with underscores

[ganyicz]

The scenario

Components with underscores in their tag names are not parsed correctly by Blaze:

<x-my_component />

The problem

Our tag name and slot name regexes don't match Laravel's ComponentTagCompiler.

Ours:

// tag name
'/^[a-zA-Z0-9-\.:]+/'
// slot name
'/^[a-zA-Z0-9-]+/'

Laravel's:

// tag name
'[\w\-\:\.]*'
// slot name
'\w+(?:-\w+)*'

\w includes underscores (and is Unicode-aware), [a-zA-Z0-9] doesn't.

The solution

Introduced LaravelRegex — a class for regex patterns sourced from Laravel's ComponentTagCompiler:

/**
 * ...every constant in this class MUST match the corresponding regex
 * in Laravel's source exactly. Do not modify these without first
 * verifying the change against Laravel...
 */
class LaravelRegex
{
    /**
     * @see ComponentTagCompiler::compileOpeningTags()     — x[-\:]([\w\-\:\.]*)
     * @see ComponentTagCompiler::compileSelfClosingTags() — x[-\:]([\w\-\:\.]*)
     * @see ComponentTagCompiler::compileClosingTags()     — x[-\:][\w\-\:\.]*
     */
    const TAG_NAME = '/^[\w\-\:\.]*/';
}

if (preg_match(LaravelRegex::TAG_NAME, $this->remaining(), $matches)) {
    return $matches[0];
}

This avoids having to test every permutation of valid tag and slot names — we're relying on Laravel's behavior directly.

Any future change requires confronting the Laravel source references.