stages/email: token_expiry format (#13394)

* Change token_expiry type from integer to text in Email Stage to unify with timedelta_string_validator

* Add migration file for token_expiry format, change from number to text field in the UI

* Fix token_expiry new format in stage.py in Email Stage

* fix linting

* Update web/src/admin/stages/email/EmailStageForm.ts

Co-authored-by: Marc 'risson' Schmitt <marc.schmitt@risson.space>
Signed-off-by: Marcelo Elizeche Landó <marce@melizeche.com>

* Use db_alias and using() for the queries

* Make valid_delta more readable

* use <ak-utils-time-delta-help> in the UI

* fix missing import

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Marcelo Elizeche Landó <marce@melizeche.com>
Signed-off-by: Jens Langhammer <jens@goauthentik.io>
Co-authored-by: Marc 'risson' Schmitt <marc.schmitt@risson.space>
Co-authored-by: Jens Langhammer <jens@goauthentik.io>

blueprints/example/flows-recovery-email-verification.yaml

@@ -57,7 +57,7 @@ entries:
       use_ssl: false
       timeout: 10
       from_address: system@authentik.local
-      token_expiry: 30
+      token_expiry: minutes=30
       subject: authentik
       template: email/password_reset.html
       activate_user_on_success: true