advagg 8.x-4.0

The drupal/advagg:4.0 needs drupal (>= 8.6)

Tasks:
#3060734 by thalles: Update dependencies of ADVAGG
#3042709 by thalles, Sergiu Stici, Arrow: Drupal 9 Deprecated Code Report
#3050458 by thalles: Remove unused line code in Asset/CssMinifier
#2953453 by idebr, matio89, jcnventura, thalles: AdvAgg CSS/JS Validator (advagg_validator) has an undeclared dependency on advagg
#3002467 by idebr, artem0793, DamienMcKenna, bonus, thalles: Using a call-time pass-by-reference is deprecated since PHP 5.3 and prohibited since PHP 5.4
#3028908 by i-trokhanenko, Roman Dyn, thalles: Use Messenger service in form
#3045913 by thalles: Unused use statement in SingleAssetOptimizerBase
#3035668 by thalles: Deprecated Unicode::substr() need to be replaced
#3035671 by thalles: Deprecated Unicode::strlen() need to be replaced
#3030082 by thalles: Duplicate documentations on hook_cron
#3030076 by thalles: Drupal dependency injection on Commands/AdvaggCommands.php
#3030064 by thalles: All dependencies must be prefixed with the project name
#3030037 by thalles: Unused variable and unused use statement
#3028470 by thalles: use function t() on advagg_cdn/src/Form/SettingsForm
#3028469 by thalles: use function t()
#3027629 by thalles, sean_e_dietrich: Replace deprecated REQUEST_TIME
#3028090 by thalles: Injection app root on advagg_ext_minify\Asset\Minifier
#3027906 by thalles: Use the config service on JsMinifier.php
#3027631 by sean_e_dietrich: use function t() OparetaionsForm
#3027632 by thalles, sean_e_dietrich: Replace deprecated drupal_set_message on advsgg.module
#3027629 by thalles: Replace deprecated REQUEST_TIME on settings form
#2979308 by Martijn Snapper: Blank page when inlining loadCSS and module disabled
#2973308 by grathbone: htmlspecialchars() expects parameter 1 to be string
#2988627 by idebr: Orphaned advagg_mod.settings.ga_inline_to_file configuration causes schema error

Bugs:
#2996683 by void--, smokris, kentr: "dns-prefetch" incorrectly uses just the domain when it should include a protocol prefix
#2949100 by Ser_Mir, pmagunia, joelstein, idebr, leymannx, andrey.troeglazov: Broken Drush 9 commands and aggregated files cleanup
#2897869 by dimag, JeroenT, NickWilde, carsonw, thalles: Advagg minification breaks CSS
#3028910 by i-trokhanenko, thalles: Title in bypass-timespan field is not translated
#2998702 by osab, hswong3i, idebr, thalles: Advagg Validator duplicates Core's "Performance" tab in Performance section
#2988628 by idebr: advagg_css_minify.settings.add_license is not defined in advagg_css_minify.schema.yml
#2790693 by lahoosascoots, aellison, NickWilde: Performance tab rendered twice in Performance section