fix(type-safe-api): fix documentation and ensure java resources dir e…

…xists (#461)

* fix(type-safe-api): ensure generated java infrastructure resources dir exists during first build

Fixes an issue where `.api.json` couldn't be copied into the resources directory during first build
since the directory didn't exist.

* docs(type-safe-api): update java and python projenrc examples to use typescript

Given that nx-monorepo currently only supports writing your .projenrc in TypeScript, we update the
docs accordingly. The examples still show how to set up projects for writing CDK and lambdas in the
respective languages.

fix #457