Ability to use <script> element for initial page data

[skryukov]

This PR:

• adds ability to use <script> element for initial page data via a new use_script_element_for_initial_page config option (see Optimize page data size and parsing (37% size reduction!) inertia#2687 and Ability to use <script> element for initial page data inertia-laravel#788)
• adds a new inertia_root helper and ability to set custom DOM id for the root element via inertia_root(id:) or a root_dom_id config option
• adds docs around all view helpers Inertia Rails provides