Add ability to handle multiple intercepts per pid.

While doing this, refactor the intercept code to be easier to understand.

The primary use case for this is to perform a parallel stack dump (both Java and native) for specific ANRs.

Add tests for all of the different intercept conditions.

Modify the tests to display the error message from the intercept
response if there is an error.

Bug: 254634348
Test: All unit tests pass.
Test: Ran debuggerd on native and java processes.
Test: Created a bugreport without error.
Change-Id: Ic531ccee05b9a470748b815cf109e0076150a0b6