feat(ngModelOptions): add allowInvalid option

This option allows to write invalid values to the model instead of having them become undefined.
Use this together with calling `ctrl.$setValidity` directly for displaying errors
from serverside validation.

Closes #8290
Closes #8313
docs(CHANGELOG.md): add changes for 1.3.0-rc.1 and 1.2.24
feat(input): support multiple attribute for email

Closes #6032