Add submitter email field to form and add modal to collect user email upon login

[cristina-stonepedraza]

Addresses microbiomedata/issues#1106

1. Make the submitter email required in the Submission Portal form

• Added a new field for this in the form (StudyForm.vue), and made it required
• Added appropriate definitions for new field (index.ts, definitions.ts)
• The field is auto-populated using the email saved in the logged-in user's details (saved in db)

2. Re-worked logic in auth.py

• Re-ordered email check (now checks if email is missing first, then checks for ORCID email instead of the other way around)
• Changed API return from XML to JSON

3. Added modal to get the user's email if it is still missing after login (this is required to create a portal submission)

• Created a new file at /web/src/views/SubmissionPortal/Components/UserEmailModal.vue
• Added check (for user login and saved email) and modal call to App.vue
• Expected behavior: After login, a check is made from App.vue to see if the user is logged in and if they have an email saved. If not, then the modal will pop up, and the user will need to enter an email to close it.