Refactor and update mail templates (#35150)

- Moved mail templates to new directories.
- Added new devtest ymls.
- Embedded styles as much as possible.
- Added new translation keys for actions email.

---------

Signed-off-by: NorthRealm <155140859+NorthRealm@users.noreply.github.com>
Co-authored-by: delvh <dev.lh@web.de>

templates/mail/org/team_invite.devtest.yml

@@ -0,0 +1,13 @@
+Inviter:
+  DisplayName: Inviter Display Name
+
+Team:
+  Name: Team name
+
+Organization:
+  DisplayName: Organization Display Name
+
+InviteURL: http://localhost/org/team/invite
+
+Invite:
+  Email: invited@example.com