- #2722
- make communication of errors from formatters to `BodyModelBinder` explicit
- `JsonInputFormatter` now adds errors to `ModelStateDictionary` with correct key
- change `InputFormatter.SelectCharacterEncoding()` to add an error and return `null` when it fails
- one less `Exception` case and removes some duplicate code
nits:
- improve some doc comments (more `<inheritdoc/>`, `<paramref/>` and `<see/>`)
- add another two `BodyValidationIntegrationTests` tests
