Prevent missing export of symbols for node and python

[jamesx-improving]

During this release cycle, we had some last minute fixes due to missing exports of our node and python clients. We would like to create a mechanism, preferably automated, to dynamically identfy even newly added public symbols that should be part of the API, but isn't included in either node/npm/glide/index.ts for node, or python/python/glide/__init__.py for python.

One approach is to utilize Abstract Syntax Tree modules (ast module for python, and TypeScript compiler API for node) to get all public symbols programmatically, and compare them with __all__ or module.exports list.

Another worth noting point for python is, unlike node, being included in the __all__ list is actually not required for end users to import a symbol. User should still be able to import it with the full package structure, as public symbols are always accessable in python. Although we probably still want to maintain this list for consistency reason, it could be considered as less critical when some symbols are missing from the __all__ list, comparing to node.

Proposed Solution: Add an integration test for each language that compares all exported (symbols) Types/Functions/Classes/enums in the released package with the list of all public Types/Functions/Classes/enums. This list should be 'similar', and all differences should be explicit.

This list should be exactly the same as the list defined in #2377

[acarbonetto]

Design discussion for: #2335

[acarbonetto]

A point to make about the Integration Test:
IT test should compare all symbols created by the release artefact and compare with the list of publicly defined symbols. This list will not match exactly, as we are purposefully allowing exporting some symbols with the package. This IT test should contain the exhaustive list of all symbols purposefully blocked. Any new public symbol added to the package, must then either be added to the IT test as blocker OR added to the __init__ or npm/glide/index.ts file for export (or else the IT test will fail and block PR pushes).