refactor(ts-types): TypeScript generator uses combined JSON Schema.

[pcornish]

Uses a combined JSON Schema document as the input for TypeScript type generation.

Background

• The Java type generator uses a combined JSON Schema, as of #101
• Historically, the TypeScript generator used separate schema files, which led to duplication of types

What changed

• The TypeScript generator now uses a combined schema file as its input, to align it to the Java generator
• This has allowed further file structure simplifications, following #104

Testing it

• Follow the prerequisites in code-generators/typescript-types/README.md
• Run scripts/generate_ts_types.sh, which
  • produces a combined schema file under code-generators/typescript-types/schemas
  • generate types under code-generators/typescript-types/dist
• Test with the example project (examples/typescript-node):
  • Replace the dependency in package.json with a local dependency: npm install ../../code-generators/typescript-types/dist
  • Run the example project (see its readme), which consumes it without any type errors

[pcornish]

...

• It would be nice if we could get rid of the Class suffixes!

Yes, I agree 👍

I've raised #112 to cover this.