feat(ui): SE billing UI (PLATFORM ONLY)

Description

Merged all UI Billing MRs into a single MR:

• feat(ui): billing page - !711 (closed)
• fix(ui): update instances table columns (#493 (closed)) - !714 (closed)
• feat(ui): Install DLE SE from the Postgres.ai Platform (platform#219) - !691 (closed)

Related issue

Examples

Checklist

• MR description has been reviewed
• MR changes are functionally tested
• MR does NOT have API/CLI changes OR there are API/CLI changes and they have been reviewed & DOCS ARE ADJUSTED (reference doc, etc)
• MR does NOT have UI changes OR there are UI changes and they have been reviewed & UX IS REVIEWED