SchemaJsonLocater does not support async schema retrieval

[RohitPtnkr1996]

The async function getSchema() within SchemaJsonLocater internally calls getSchemaSync to get a schema.
So, the function is not truly async.

To make the function async, we need to revisit the schema json loading and make that function async (which it currently isn't).
Alternatively, we can create a new schema locater to specifically handle async operations.

[grigasp]

Out of curiosity, why does this have the breaking change label?

[RohitPtnkr1996]

I had added it as a possible breaking change until we decide what approach to take.
If we're creating a new async json loader.
Or if we're updating the existing one, in which case the caller that gets the json will need to be async as well.

I'll update the label once I pick this up.