Add support for WP_ENVIRONMENT_TYPE

New behaviour:

1. Resolve the environment type:
	1. Use the value of the `WP_ENV` constant if defined and palpable.
	2. Otherwise, use the value of the `wp_get_environment_type()` function if defined (introduced in WordPress 5.0.0).
	3. Otherwise, use `NULL`.
2. Filter the environment type with the following hook:
	* `roots/bedrock/disallow_indexing_environment_type`
3. Display the notice:
	1. If the environment type is palpable, display the notice with the filtered environment type.
	2. Otherwise, display a shorter notice that does not reference the environment type.

Author: mcaskill

README.md

@@ -28,4 +28,4 @@
 
 ## Overview
 
-This plugin will prevent indexing of a site when `WP_ENV` is not set to `production`.
+This plugin will prevent indexing of a site when [`WP_ENV`](https://docs.roots.io/bedrock/master/environment-variables/#wp-env) or [`wp_get_environment_type()`](https://developer.wordpress.org/reference/functions/wp_get_environment_type/) is not set to `production`.

bedrock-disallow-indexing.php

@@ -22,11 +22,28 @@
     }
 
     add_action('admin_notices', function () {
-        $message = sprintf(
-            __('%1$s Search engine indexing has been discouraged because the current environment is %2$s.', 'roots'),
-            '<strong>Bedrock:</strong>',
-            '<code>'.WP_ENV.'</code>'
-        );
+        if (defined('WP_ENV') && WP_ENV) {
+            $wp_env = WP_ENV;
+        } else if (function_exists('wp_get_environment_type')) {
+            $wp_env = wp_get_environment_type();
+        } else {
+            $wp_env = null;
+        }
+
+        $wp_env = apply_filters('roots/bedrock/disallow_indexing_environment_type', $wp_env);
+        if ($wp_env) {
+            $message = sprintf(
+                __('%1$s Search engine indexing has been discouraged because the current environment is %2$s.', 'roots'),
+                '<strong>Bedrock:</strong>',
+                '<code>'.$wp_env.'</code>'
+            );
+        } else {
+            $message = sprintf(
+                __('%1$s Search engine indexing has been discouraged.', 'roots'),
+                '<strong>Bedrock:</strong>'
+            );
+        }
+
         echo "<div class='notice notice-warning'><p>{$message}</p></div>";
     });
 });