`expect(...).toMatch*Snapshot` methods do not have `Promise` return types

[kmaglione]

These functions are all typed to return void rather than Promise<void>, which causes TypeScript to emit a hint that await has no effect, and causes the ESLint @typescript-eslint/await-thenable rule to emit an error.

There aren't any particularly clean workarounds for this issue. I handled it by creating a wrapper function, but that ended up being particularly ugly given that WdioCheckElementMethodOptions isn't exported anywhere.

[wswebcreation]

Closing this as it's fixed in #1097

[kmaglione]

Thanks!