Fixed custom validation context bug where child
associations were not being saved.

Fixes #13854.

[Eric Chahin, Aaron Nelson, & Kevin Casey]
Use #include? instead of #any?, make it simpler
Test typecasting on instance rather than class itself
Merge pull request #14957 from akshay-vishnoi/test-cases

Test typecasting on instance rather than class itself
Merge pull request #14956 from akshay-vishnoi/refactor

Use #include? instead of #any?, make it simpler
Merge pull request #14924 from eric-chahin/issue_13854

Fixed custom validation context bug for child associations