Add feature flag for Codex Special:Block UI

Introduce a temporary feature flag that will be used to display
Special:Block UI in Codex.

Bug: T358153
Change-Id: I74bc90af986ac2f429a952a19b6edf4fb02c5618

docs/config-schema.yaml

@@ -7938,3 +7938,9 @@ config-schema:
         default: 2592000
         type: integer
         description: 'Number of seconds to keep edit recovery data after the edit is stored.'
+    UseCodexSpecialBlock:
+        default: false
+        type: boolean
+        description: |-
+            Whether to use Codex in Special:Block form.
+            This is a temporary feature flag.

docs/config-vars.php

@@ -4416,3 +4416,9 @@ $wgEnableEditRecovery = null;
  * @see MediaWiki\MainConfigSchema::EditRecoveryExpiry
  */
 $wgEditRecoveryExpiry = null;
+
+/**
+ * Config variable stub for the UseCodexSpecialBlock setting, for use by phpdoc and IDEs.
+ * @see MediaWiki\MainConfigSchema::UseCodexSpecialBlock
+ */
+$wgUseCodexSpecialBlock = null;

includes/MainConfigNames.php

@@ -4432,4 +4432,10 @@ class MainConfigNames {
 	 */
 	public const EditRecoveryExpiry = 'EditRecoveryExpiry';
 
+	/**
+	 * Name constant for the UseCodexSpecialBlock setting, for use with Config::get()
+	 * @see MainConfigSchema::UseCodexSpecialBlock
+	 */
+	public const UseCodexSpecialBlock = 'UseCodexSpecialBlock';
+
 }

includes/MainConfigSchema.php

@@ -12716,6 +12716,15 @@ class MainConfigSchema {
 		'type' => 'integer',
 	];
 
+	/**
+	 * Whether to use Codex in Special:Block form.
+	 * This is a temporary feature flag.
+	 */
+	public const UseCodexSpecialBlock = [
+		'default' => false,
+		'type' => 'boolean',
+	];
+
 	// endregion -- End Miscellaneous
 
 }

includes/config-schema.php

@@ -2503,6 +2503,7 @@ return [
 			],
 			'EnableEditRecovery' => false,
 			'EditRecoveryExpiry' => 2592000,
+			'UseCodexSpecialBlock' => false,
 		],
 		'type' => [
 			'ConfigRegistry' => 'object',
@@ -2976,6 +2977,7 @@ return [
 			'SpecialContributeSkinsEnabled' => 'array',
 			'EnableEditRecovery' => 'boolean',
 			'EditRecoveryExpiry' => 'integer',
+			'UseCodexSpecialBlock' => 'boolean',
 		],
 		'mergeStrategy' => [
 			'TiffThumbnailType' => 'replace',