Refactor header.php and enable Woo parts if WooCommerce is installed

[crftwrk]

In relation to #460

This PR uses get_template_part to get header buttons/widgets. WooCommerce related items load when WooCommerce is installed. No 2 different header.php's needed anymore.

• No breaking changes to existing bootcommerce-child installations
• Allows us to delete header.php in bootcommerce-child

How to test

Test in main-theme

• Remove // comments in main.scss line 4 to enable Woo styles
• Add following snippet to functions.php to enable Woo scripts if Woo is installed

if ( class_exists( 'WooCommerce' ) ) {

  require get_template_directory() . '/woocommerce/woocommerce-functions.php';
  
  function my_function() {
    echo '<p class="alert alert-success">Woo installed</p>';
  }
  add_action('bs_after_primary', 'my_function', 5);

} else {

function my_function_2() {
    echo '<p class="alert alert-warning">Woo NOT installed</p>';
  }
  add_action('bs_after_primary', 'my_function_2', 5);

}

• Enable/disable WooCommerce plugin in backend and check the header in frontend
• Install a usual bootscore-child and override parts or entire header templates

@justinkruit

• If you like it, merge it
• Is there a way to add _bscore_woocommerce.scss to the compiler and enable file only if WooCommerce is installed?

[justinkruit]

Maybe an idea to move the files a bit? Instead of them being named header-top-nav-search-collapse-woocommerce.php, name them header/top-nav-search-collapse-woocommerce.php, and that way you can call this one via get_template_part('template-parts/header/top-nav-search-collapse', 'woocommerce'); (as woocommerce is a variant of that file)

[crftwrk]

Good idea, pls check. I removed some comments because snippets speak by itself.

[justinkruit]

Looks great, good job on this 👍