BREAKING: Typescript upgrade + type audit

[charliecruzan-stripe]

Summary

• Upgraded typescript to v4.4.4
• Move to relying on modules rather than namespaces
• Moved to just one format for describing addresses
• Setup better naming conventions on Types
• Fixed some Type bugs (closes Wrong type definition for presentGooglePay #799)
• Removed unused types

Motivation

Some types didn't make much sense in terms of their names, and we also had some inconsistent naming. This also made it difficult to identify bugs and add new features.

Testing

• I tested this manually
• I added automated tests

Documentation

Select one:

• I have added relevant documentation for my changes.
• This PR does not result in any developer-facing changes.

[fbartho]

I've tested none of this and I'm not a regular contributor, but the changes I see look great!
I love the improvements to typing, and code organization, and parameter names.

The breaking change section may need to be expanded or a migration guide provided for non-TypeScript consumers of this SDK.

[arekkubaczkowski]

that is really nice to see that this library is actively maintained and still evolving! I noticed a huuuge progress and it's really amazing