feat: port md based changelog to json, improve structure (planning#874)

CHANGELOG.md

src/components/changelog/ChangelogEntry.tsx

src/components/changelog/ChangelogFilter.tsx

src/components/changelog/ChangelogList.tsx

src/components/changelog/ChangelogReleaseTable.tsx

src/components/changelog/ServiceReleaseNotes.tsx

src/components/changelog/types.ts

src/pages/changelog.tsx

static/changelog/changelog.json