Avoid leaving temp files in hidden docker layers

Fix broken dashcard CSS classes

Docker documentations improvements

Add new kanye quote

Add starttls smtp authentication

Don't hide widget filter if filtered result is empty

Improvements to E2E testing workflow

Add a space between New and Question words in navbar button

* fixes issue 4758

* refactor into own component

* fix #4693 & #4769 + tests

* add flow types

* don't actually need this

* better flow types

fix db-pre-migration not running on postgres

Fix watching files changes for webpack-dev-server

Auto-resizing embeds

Fix timeseries widgets wonkiness

Adds the option to require smtp connections to use STARTTLS
authentication. This is distinct from SSL and TLS and usually shares a
port with unencrypted connections. This change enables starttls for
the connection and makes it required. This appears as it's own
security setting in the email configuration.

fixes: https://github.com/metabase/metabase/issues/4272

Getting Started Guide fixes

Frontend dependency updates