(feat) Implement configurable enabledErrorTypes

[robinmacharg]

Goal

To allow users to configure the types of event that are reported.

Design

This is implemented as a bitfield on BugsnagConfiguration. BugsnagSentry translates this to equivalent KSCrash values. The OOM value is examined in BugsnagNotifier. The bitfield mapping has been broken out to make it testable.

Changeset

As above, BugsnagConfiguration, BugsnagSentry and BugsnagNotifier.

Tests

This is difficult to test at unit-level. What can be has been. E2E tests better test the behaviour and this is where the effort has been concentrated.

Review

Outstanding Questions

• E2E Testing is extensive but I have lingering doubts over whether it's comprehensive. There's ambiguous behaviour around e.g. Mach errors being converted to Signals.

• This pull request is ready for:
  • Initial review of the intended approach, not yet feature complete
  • Structural review of the classes, functions, and properties modified
  • Final review

• The correct target branch has been selected (master for fixes, next for
  features)
• Consistency across platforms for structures or concepts added or modified
• Consistency between the changeset and the goal stated above
• Internal consistency with the rest of the library - is there any overlap between existing interfaces and any which have been added?
• Usage friction - is the proposed change in usage cumbersome or complicated?
• Performance and complexity - are there any cases of unexpected O(n^3) when iterating, recursing, flat mapping, etc?
• Concurrency concerns - if components are accessed asynchronously, what issues will arise
• Thoroughness of added tests and any missing edge cases
• Idiomatic use of the language

[robinmacharg]

Note to self: I need to check e2e on Mac vs iOS.