Fix (suppress) var-naming ansible-lint errors

Reference: https://ansible-lint.readthedocs.io/en/latest/default_rules/#var-naming

We don't really fix these, but just suppress them,
because they're like that intentionally.

We try to name variables in a way that is consistent with the
configuration key they control. If the upstream component uses
camelCase, we also need to include camelCase in the variable name.

roles/matrix-client-element/tasks/prepare_themes.yml

@@ -26,7 +26,7 @@
 
   - name: Load Element theme
     ansible.builtin.set_fact:
-      matrix_client_element_settingDefaults_custom_themes: "{{ matrix_client_element_settingDefaults_custom_themes + [item['content'] | b64decode | from_json] }}"
+      matrix_client_element_settingDefaults_custom_themes: "{{ matrix_client_element_settingDefaults_custom_themes + [item['content'] | b64decode | from_json] }}"  # noqa var-naming
     with_items: "{{ matrix_client_element_theme_file_contents.results }}"
 
   run_once: true