feat: Add the email input box for encrypt form modal

[g-tejas]

Problem

https://www.notion.so/opengov/Allow-inputting-email-recipients-on-form-creation-13777dbba78880619402dd8d48ab7209

Breaking Changes

• No - this PR is backwards compatible

Before & After Screenshots

Before	After

Tests

Encrypt forms

• 1. Create encrypt mode form
• 2. Observe that the admin email is inserted by default
• 3. Observe that the email input field is optional, you're allowed to remove it and leave it empty
• 4. Add your email, and create the form. Navigate to the email settings page
• 5. Observe that the email inputted earlier exists (or empty if not included earlier)

Duplicated forms

• 1. Create an email mode form, with the admin email inside.
• 2. Duplicate that form to encrypt mode
• 3. Observe that the email input is present, and is optional
• 4. Observe that the emails are carried over from the duplicated form.