Make self-check not validate self-signed certificates

By default, `--tags=self-check` no longer validates certificates
when `matrix_ssl_retrieval_method` is set to `self-signed`.

Besides this default, people can also enable/disable validation using the
individual role variables manually.

Fixes #124 (Github Issue)

roles/matrix-mxisd/defaults/main.yml

@@ -55,6 +55,9 @@ matrix_mxisd_threepid_medium_email_custom_session_validation_template: ""
 matrix_mxisd_threepid_medium_email_custom_unbind_fraudulent_template: ""
 matrix_mxisd_threepid_medium_email_custom_matrixid_template: ""
 
+# Controls whether the self-check feature should validate SSL certificates.
+matrix_mxisd_self_check_validate_certificates: true
+
 # Default mxisd configuration template which covers the generic use case.
 # You can customize it by controlling the various variables inside it.
 #

roles/matrix-mxisd/tasks/self_check_mxisd.yml

@@ -7,6 +7,7 @@
   uri:
     url: "{{ mxisd_url_endpoint_public }}"
     follow_redirects: false
+    validate_certs: "{{ matrix_mxisd_self_check_validate_certificates }}"
   register: result_mxisd
   ignore_errors: true