Support for `infer` in template literals, intrinsic types and more

[flugg]

Closes https://github.com/vega/ts-json-schema-generator/issues/1355

Adding full type inference for template literals were quite a lot more work than first anticipated, particularly because TemplateLiteralNodeParser would narrow the type to a LiteralType, StringType or UnionType before sent to isAssignableTo in ConditionalNodeParser. My proposed solution is to add a check within TemplateLiteralNodeParser to see if the node exists within an extends clause of a conditional, in which case we create a new TemplateLiteralType where we retain the original information stored in the template literal, which allows us to segment through the parts and verify if the source is assignable.

Additionally, I've done the same for IntrinsicNodeParser, which had the same limitations, where both StringType and InferType as an argument in a condiitonal type would fail.

I've added extensive test cases for both.