PR 4241 fix

[Andyvargtz]

• Discussion: should we keep the country lock?
• Tech_stack should allow for non listed options (see skills component for reference)
• Translations in GeneralSecure (and others) should be handled by i8n mechanism already in place

Staged Hackathon not considered in scope

• Include tech_stack questions in staged forms.
• % Submission leads to legacy submission form even if it's a staged hackathon

Team Formation

• UX: Inputing the emails in teamFormation should reuse the email input component we have in teamFormation

• Invitation emails embed the hackathon banner as a base64 data-URI , which in case of being big enough pushes the HTML past Gmail's ~102KB limit (causing the "[Message clipped]" truncation and an empty black box, since clients also block data: images). Include validation and default image or just generic one.