v1.2.0: Communicate Across Layers

[confused-Techie]

The major underlying change of this PR is to allow the different 'layers' of the backend (http handler, database, object construction, etc) to more easily communicate, mainly with the http handler itself.
Doing this requires significant other changes, and allows quite a few new features.

Below is a messy list of goals to include:

• Migrate tests to only test the HTTP endpoints themselves.
• Define a more flexible endpoint invocation method, to allow easier changing of the application context
• Simplify the heavy usage of early return patterns
• Support and implement the Server-Timing HTTP Header
• Group logs by transaction ID and wrap them for GCP when in a GCP environment
• Support and adopt the Problem Details specification for errors