fix(rosetta): Rosetta is not submodule-aware

[rix0rrr]

Rosetta was not properly aware of submodules and namespaces, at all. This manifested in two different ways:

• Imports of (Python) modules from submodules were not translated properly
• Synthetically generated struct constructors were not namespaced with a proper import.

The translation of a call involving a struct:

import { aws_ec2 as ec2 } from 'aws-cdk';

const construct = new ec2.MyConstruct('some', 'values', {
  arg: { ...  }
});

Used to be translated into this:

from aws_cdk import aws_ec2 as ec2

construct = ec2.MyConstruct('some', 'values',
    arg=DeeperStruct(...)
    )

Notice that DeeperStruct is missing the module prefix that would
allow this code to work.

We trace what jsii FQNs every imported symbol refers to, and see
if we can reuse an import that already exists to retrieve our struct.
If not, we'll generate a new import at the top of the example.

To properly track what is being imported in an example (if it's a class or
a module, or potentially a submodule) we needed to be able to identify
submodules in TypeScript source, so we've also attached a symbolId
to submodules in the jsii assembly.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[rix0rrr]

NOTE: not complete yet for submodules. Requires #3174 to finish.

[mergify]

Thank you for contributing! ❤️ I will now look into making sure the PR is up-to-date, then proceed to try and merge it!

[mergify]

Merging (with squash)...

[mergify]

Merging (with squash)...