R1:1fc60a9a6e70

Modularize Aphront exception handling

Summary:
Ref T1806. Ref T7173. Depends on D14047.

Currently, all exception handling is in this big messy clump in `AphrontDefaultApplicationConfiguration`.

Split it out into modular classes. This will let a future change add new classes in the Phacility cluster which intercept particular exceptions we care about and replaces the default, generic responses with more useful, tailored responses.

Test Plan:
{F777391}

- Hit a Conduit error (made a method throw).
- Hit…