Need access to a Context statically; currently not obtainable from application constructor

One approach would be to expose a method for getting the base context (parent of application) on InstrumentationRegistry, and that could be seeded in newApplication() in MonitoringInstrumentation.

Imported from b/76147120

Start by reading InstrumentationRegistry and MonitoringInstrumentation, especially newApplication(), to understand how the base context is currently initialized. Confirm the intended static access point and verify that the base context is available after application setup; the issue does not name a test file to run.

Written by the indexing model from the issue text.