MDL-82657 qbank_managecategories: Check "includesubcategories" on reload

The "includesubcategories" parameter is passed in the URL as lowercase,
but the Javascript was looking for "includeSubcategories" in camel case.
This meant it was always being set as false (unchecked) even when the
URL said it was true.

This fixes the casing in the Javascript, and adds a behat test to
confirm the fix.

question/bank/managecategories/amd/src/datafilter/filtertypes/categories.js

@@ -31,9 +31,9 @@ export default class extends GenericFilter {
         includeSubcategories: 'input[name=category-subcategories]',
     };
 
-    constructor(filterType, rootNode, initialValues, filterOptions = {includeSubcategories: false}) {
+    constructor(filterType, rootNode, initialValues, filterOptions = {includesubcategories: false}) {
         super(filterType, rootNode, initialValues);
-        this.addSubcategoryCheckbox(filterOptions.includeSubcategories);
+        this.addSubcategoryCheckbox(filterOptions.includesubcategories);
     }
 
     async addSubcategoryCheckbox(checked = false) {

question/bank/managecategories/tests/behat/question_categories.feature

@@ -99,3 +99,6 @@ Feature: A teacher can put questions in categories in the question bank
     When I set the field "Also show questions from subcategories" to "1"
     And I click on "Apply filters" "button"
     Then I should see "Question 1" in the "categoryquestions" "table"
+    When I reload the page
+    Then I should see "Question 1" in the "categoryquestions" "table"
+    And the field "Also show questions from subcategories" matches value "1"