Inject dependencies

Problem/Motivation

phpstan reports,

------ ----------------------------------------------------------------------
Line src/Form/IdpDeleteForm.php
------ ----------------------------------------------------------------------
68 \Drupal calls should be avoided in classes, use dependency injection
instead
🪪 globalDrupalDependencyInjection.useDependencyInjection
------ ----------------------------------------------------------------------
------ ----------------------------------------------------------------------
Line src/SAML/SamlSPAuth.php
------ ----------------------------------------------------------------------
101 \Drupal calls should be avoided in classes, use dependency injection
instead
🪪 globalDrupalDependencyInjection.useDependencyInjection
108 \Drupal calls should be avoided in classes, use dependency injection
instead
🪪 globalDrupalDependencyInjection.useDependencyInjection
132 \Drupal calls should be avoided in classes, use dependency injection
instead
🪪 globalDrupalDependencyInjection.useDependencyInjection
------ ----------------------------------------------------------------------
------ ----------------------------------------------------------------------
Line src/SAML/SamlSPAuthnRequest.php
------ ----------------------------------------------------------------------
18 \Drupal calls should be avoided in classes, use dependency injection
instead
🪪 globalDrupalDependencyInjection.useDependencyInjection
------ ----------------------------------------------------------------------
------ ----------------------------------------------------------------------
Line src/SAML/SamlSPSettings.php
------ ----------------------------------------------------------------------
45 \Drupal calls should be avoided in classes, use dependency injection
instead
🪪 globalDrupalDependencyInjection.useDependencyInjection
------ ----------------------------------------------------------------------

Steps to reproduce

see https://git.drupalcode.org/project/saml_sp/-/jobs/6337727

Proposed resolution

• In IdpDeleteForm, use $this->messenger that comes with MessengerTrait..
• In SamlSPAuth, use MessengerTrait and pass config in when instantiating the class in .module.
• In SamlSPAuthnRequest, pass config in when instantiating the class in SamlSPAuth.
• In SamlSPSettings, use MessengerTrait.

Remaining tasks

Make a MR.