For TypeScript 2.9, TSLint service should provide the way to ignore error in JSON module

[Soul-Master]

In TypeScript 2.9, external module can reference to other JSON module. TSLint language service should allow us to ignore JSON files just like TypeScript definition files. I try to exclude JSON file in tslint/typescript config. But it doesn't work.

The following code can fix this issue on VS2017.
fig.ignoreDefinitionFiles === true && fileName.endsWith('.json')) { return prior; }