Collapsible TO, CC, BCC, and FROM Fields

Is your feature request related to a problem? Please describe.

When composing an email with recipients added in the TO, CC, BCC, and FROM fields, alongside attachments, the available space for the email body becomes significantly small. To improve the user experience, I propose making these fields collapsible, allowing users to expand or collapse them as needed.

In scenarios where multiple recipients are added across all fields (TO, CC, BCC, and FROM) and attachments are included, the input space for the email body is reduced, making it difficult to focus on writing the message.

Describe the solution you'd like

Have a collapsible UI for the TO, CC, BCC, and FROM fields.
Users should be able to collapse these fields after entering the recipients, freeing up space for the body section.
The fields can be expanded again if the user needs to edit or review them.

Describe alternatives you've considered

Open for any other ideas @jancborchardt @nimishavijay @marcoambrosini

Additional context