* chore: rename Oauth to OAuth

* minor: simplified validations for email account

* keep server and port together

Since the places where connection methods are called already
have a lot of exception handling, we can just raise and let them
handle all the probable cases.

* chore: raise not implemented error for services other than gmail

* chore: use fstring for _auth_string property

This will help in knowing the original email id and sender of email
and also bring consistency.

kinda works in a similar way as awaiting_password for new emails

* used unique constraint on email_id in Email Account Doctype

* refactor: single callback method for google oauth

This is now configurable with log settings.

This also fixes circular import issue that occurs when restoring backup

User Mention cache is deleted on 3 occasions:

* when a new user is inserted
* when allowed_in_mention or user_type value has changed
* when a user is deleted

But we didn't delete it when a user was enabled or disabled as we maintain the mention cache for enabled users

IMO strikethrough is useful way more often (than many other options that we
already support in editor) so adding it in default config.

closes #17470

Container uses bubble type quill editor, options for which seem to spill
out and hide behind the commend container. This fixes the UI glitch.

ref: https://quilljs.com/docs/configuration/#bounds

* fix: dont scrub key if found in defaults, but falsy

* fix: remove redundant use of `.get`

Sometimes it might take more than 5s

perf: Re-use SMTP session while sending bulk emails

fix: Preserve data type in excel export except for composite