Improve options handling

[jdevalk]

Use one option instead of multiple

We should have one edac option which is an array with keys for all the things we need to store. No need for the many different options we have right now.

Instead of this:

add_option( 'edac_activation_date', gmdate( 'Y-m-d H:i:s' ) );
add_option( 'edac_post_types', array( 'post', 'page' ) );
add_option( 'edac_simplified_summary_position', 'after' );

We should be doing:

add_option( 'edac', [
  'activation_date'             => gmdate( 'Y-m-d H:i:s' ),
  'post_types'                  => [ 'post', 'page' ],
  'simplified_summary_position' => 'after',
] );

Ideally, we'd make a single options class which we use for all interactions with our single option. For example, something like this.

No need to add_option

This code:

if ( get_option( $option_name ) !== false ) {
    update_option( $option_name, $new_value );
} else {
    add_option( $option_name, $new_value );
}

can simply be

update_option( $option_name, $new_value );

If the option doesn't exist, it will be created. WP already takes care of these things.