- #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
- use `[ConditionalFact]` or `[ConditionalTheory]` instead
- in some cases test was already conditional
- move other `IsMono` checks into data sets where possible
- not reported as skipped but at least not counted as successful
nit: switch from `[ConditionalTheory]` to `[ConditionalFact]` as appropriate
- slightly more efficient since xUnit won't check for data