LG-3237: React internationalization string element interpolation

[aduth]

Why: Localized strings may contain HTML markup, which React will escape by default. This provides a mechanism to be able to safely replace intended HTML markup with equivalent React elements substitutes.

See inline code documentation for formatHTML for more details, limitations, etc.

Before	After

[aduth]

This gives me pause. Technically the u here is a component, and the rule should apply to all components. But I'm also motivated to not over-complicate how one interfaces with formatHTML to impose that they define a separate component function with its own propTypes, defaultProps, etc. Conversely, I could have chosen to not assign the "handlers" mapping with the value being of type Component, and instead more of a generic "function which returns an element". The nice thing about this usage is that you could choose to extract or reuse a traditional component here (e.g. { button: MyFancyButton }).

I see some value in having the rule in general, in how it's self-documenting and provides some availability of type-hinting for capable IDEs.

But it's also something where, if we decide to integrate more of the TypeScript tooling, it's completely redundant with standard JSDoc function parameter documentation (where the parameter is the props object of a particular shape).

[zachmargolis]

LGTM