fix: React class component defaultProps types

[bvandercar-vt]

Fixes #6899

Checklist

• [N/A] Includes tests
• [N/A] Update documentation

Changes proposed in this pull request:

See issue in https://github.com/palantir/blueprint/issues/6899

Setting defaultProps to a type of Partial<Props> makes all component props partial, which could lead to disastrous effects. TypeScript advises against this starting with TS v3.0:

https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-0.html#explicit-types-on-defaultprops

If an explicit type annotation is added, e.g. static defaultProps: Partial<Props>; the compiler will not be able to identify which properties have defaults

Use static defaultProps: Pick<Props, "name">; as an explicit type annotation instead, or do not add a type annotation as done in the example above.