Create Metadata pinia store

src/api/metadata.ts

src/components/Element/DetailsPanel.vue

src/components/Element/Metadata/Metadata.vue

src/store/elements.js

src/store/index.js

src/stores/index.ts

src/stores/metadata.ts

src/types/index.ts

tests/unit/store/elements.spec.js

tests/unit/stores/metadata.spec.js