Tool choice and required tool selection

[sixlive]

Description

Closes #21

$weather = Tool::as('weather')
    ->for('useful when you need to search for current weather conditions')
    ->withStringParameter('city', 'The city that you want the weather for')
    ->using(fn (string $city): string => 'The weather will be 75° and sunny');

Prism::text()
    ->withTools([$weather])
    ->withToolChoice(ToolChoice::Auto)
    ->withToolChoice(ToolChoice::Any)
    ->withToolChoice('weather');

[mrfelipemartins]

It would be nice to able to pass a tool class like ->withToolChoice(SearchTool::class), as described in Defining Complex Tools

[sixlive]

@mrfelipemartins great suggestion! I added support for passing Tool classes as well!