Callback before_standard_html_head in local_filemanagertexts component should be migrated to new hook callback for core\hook\output\before_standard_head_html_generation

• line 7229 of /public/lib/moodlelib.php: call to debugging()
• line 7296 of /public/lib/moodlelib.php: call to {closure}()
• line 73 of /public/lib/classes/hook/output/before_standard_head_html_generation.php: call to get_plugins_with_function()
• line 194 of /public/lib/classes/output/core_renderer.php: call to core\hook\output\before_standard_head_html_generation->process_legacy_callbacks()
• line 219 of /public/lib/mustache/src/Mustache/Context.php: call to core\output\core_renderer->standard_head_html()
• line 138 of /public/lib/mustache/src/Mustache/Context.php: call to Mustache_Context->findVariableInStack()
• line 31 of /home2/moodle51/domains/moodledata/localcache/mustache/1773084895/boost/__Mustache_73560842f9d6c5bc337558df4f13b989.php: call to Mustache_Context->findDot()
• line 13 of /home2/moodle51/domains/moodledata/localcache/mustache/1773084895/boost/__Mustache_43c0038b93d4d80bd2fd212f6027adba.php: call to __Mustache_73560842f9d6c5bc337558df4f13b989->renderInternal()
• line 66 of /public/lib/mustache/src/Mustache/Template.php: call to __Mustache_43c0038b93d4d80bd2fd212f6027adba->renderInternal()
• line 192 of /public/lib/classes/output/renderer_base.php: call to Mustache_Template->render()
• line 107 of /public/theme/boost/layout/drawers.php: call to core\output\renderer_base->render_from_template()
• line 959 of /public/lib/classes/output/core_renderer.php: call to include()
• line 875 of /public/lib/classes/output/core_renderer.php: call to core\output\core_renderer->render_page_layout()
• line 128 of /public/index.php: call to core\output\core_renderer->header()