Make withTemplates() accept folder references and in-memory declarations

[thekid]

Follows the "be liberal in what you accept" paradigm:

Loading templates from files

use com\handlebarsjs\{HandlebarsEngine, FilesIn};
use io\{Path, Folder};

$engine= (new HandlebarsEngine())->withTemplates(new FilesIn('src/main/handlebars'));

// All of these now also work:
$engine= (new HandlebarsEngine())->withTemplates('src/main/handlebars');
$engine= (new HandlebarsEngine())->withTemplates(new Path('src/main/handlebars'));
$engine= (new HandlebarsEngine())->withTemplates(new Folder('src/main/handlebars'));

Declaring templates in memory

use com\github\mustache\InMemory;
use com\handlebarsjs\HandlebarsEngine;

$declaration= ['test' => 'Hello {{name}}'];
$engine= (new HandlebarsEngine())->withTemplates(new InMemory($declaration));

// This now also works:
$engine= (new HandlebarsEngine())->withTemplates($declaration);

[thekid]

Released in https://github.com/xp-forge/handlebars/releases/tag/v9.5.0