root: global email settings (#448)

* root: make global email settings configurable

* stages/email: add use_global_settings

* stages/email: add test_email command to test email sending

* stages/email: update email template

* stages/email: simplify email template path

* stages/email: add support for user-supplied email templates

* stages/email: add tests for sending and templates

* stages/email: only add custom template if permissions are correct

* docs: add custom email template docs

* root: add /templates volume in docker-compose by default

* stages/email: fix form not allowing custom templates

* stages/email: use relative path for custom templates

* stages/email: check if all templates exist on startup, reset

* docs: add global email docs for docker-compose

* helm: add email config to helm chart

* helm: load all secrets with env prefix

* helm: move s3 and smtp secret to secret

* stages/email: fix test for relative name

* stages/email: add argument to send email from existing stage

* stages/email: set uid using slug of message id

* stages/email: ensure template validation ignores migration runs

* docs: add email troubleshooting docs

* stages/email: fix long task_name breaking task list

website/static/flows/recovery-email-verification.pbflow

@@ -92,7 +92,7 @@
                 "from_address": "system@authentik.local",
                 "token_expiry": 30,
                 "subject": "authentik",
-                "template": "stages/email/for_email/password_reset.html"
+                "template": "email/password_reset.html"
             }
         },
         {