Introduce 'insertbefore' and 'insertafter' to specify the position (#44811)

* Introduce 'insertbefore' and 'insertafter' to specify the position children have to be inserted.

* Added version_added to new options

* Xpath in example needs single quotes

* Added integration tests for insertafter and insertbefore

* Changed version_added to 2.8

test/integration/targets/xml/tasks/main.yml

@@ -37,6 +37,8 @@
 
   - include_tasks: test-add-children-elements.yml
   - include_tasks: test-add-children-from-groupvars.yml
+  - include_tasks: test-add-children-insertafter.yml
+  - include_tasks: test-add-children-insertbefore.yml
   - include_tasks: test-add-children-with-attributes.yml
   - include_tasks: test-add-element-implicitly.yml
   - include_tasks: test-count.yml

test/integration/targets/xml/tasks/test-add-children-insertafter.yml

@@ -0,0 +1,32 @@
+---
+  - name: Setup test fixture
+    copy:
+      src: fixtures/ansible-xml-beers.xml
+      dest: /tmp/ansible-xml-beers.xml
+
+
+  - name: Add child element
+    xml:
+      path: /tmp/ansible-xml-beers.xml
+      xpath: '/business/beers/beer[text()="St. Bernardus Abbot 12"]'
+      insertafter: yes
+      add_children:
+      - beer: Old Rasputin
+      - beer: Old Motor Oil
+      - beer: Old Curmudgeon
+      pretty_print: yes
+    register: add_children_insertafter
+
+  - name: Compare to expected result
+    copy:
+      src: results/test-add-children-insertafter.xml
+      dest: /tmp/ansible-xml-beers.xml
+    check_mode: yes
+    diff: yes
+    register: comparison
+
+  - name: Test expected result
+    assert:
+      that:
+      - add_children_insertafter.changed == true
+      - comparison.changed == false  # identical

test/integration/targets/xml/tasks/test-add-children-insertbefore.yml

@@ -0,0 +1,32 @@
+---
+  - name: Setup test fixture
+    copy:
+      src: fixtures/ansible-xml-beers.xml
+      dest: /tmp/ansible-xml-beers.xml
+
+
+  - name: Add child element
+    xml:
+      path: /tmp/ansible-xml-beers.xml
+      xpath: '/business/beers/beer[text()="St. Bernardus Abbot 12"]'
+      insertbefore: yes
+      add_children:
+      - beer: Old Rasputin
+      - beer: Old Motor Oil
+      - beer: Old Curmudgeon
+      pretty_print: yes
+    register: add_children_insertbefore
+
+  - name: Compare to expected result
+    copy:
+      src: results/test-add-children-insertbefore.xml
+      dest: /tmp/ansible-xml-beers.xml
+    check_mode: yes
+    diff: yes
+    register: comparison
+
+  - name: Test expected result
+    assert:
+      that:
+      - add_children_insertbefore.changed == true
+      - comparison.changed == false  # identical