#254 - add back missing type declaration for options pages.

[jasonbahl]

The underlying Options Page type declaration was removed in v0.5.0 release.

See: https://github.com/wp-graphql/wp-graphql-acf/pull/250/files?file-filters%5B%5D=.php&file-filters%5B%5D=.woff2&file-filters%5B%5D=.xml&file-filters%5B%5D=.yml&file-filters%5B%5D=dotfile#diff-a561f3a494f34edd4c3f2e83c25c8d4a9dc217eeeaed4385c735040450230ac0L1765

This PR adds it back and fixes null values being returned for option page values.

Steps to Reproduce

Adding the following Options Page:

	acf_add_options_page(array(
		'page_title' 	=> 'Theme General Settings',
		'menu_title'	=> 'Theme Settings',
		'menu_slug' 	=> 'theme-general-settings',
		'capability'	=> 'edit_posts',
		'redirect'		=> false,
		'show_in_graphql' => true,
		'graphql_field_name' => 'ThemeGeneralSettings',
	));

Then assigning an ACF Field Group to the Options Page:

Then populating the settings field:

Before

Querying the text field in the settings returns no value

After

Querying the text field in the Settings returns the expected value

Closes #254

[marekbdzoch]

Its not working for me :/ @jasonbahl