Handle validation for fields with '.' - 19.2.x

[MonikaKirkova]

Closes #15932

Changes:

1. Do not replace . in field names with _ when passing a name for the ngControl, Use the column field name as a name for the native ngControl added

2. When trying to get a control using ngControl.get, wrap the name in an array. This way ngControl.get will treat it as a literal key. Otherwise, default behavior of ngControl,get("address.street") is to look for a control named "address" and then look for a control nested named "street" , which is nested under address.

3. Assign formControl.errors in a let variable in order to be resolved once, not to be resolved once for each usage in the template

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them

[dkamburov]

I know it's an edge case, but I'm not sure about it. If we have column test.1 and test_1, we'll mess up the validation, I guess we are good with this, but should be at least very well described in the docs.

Or even better we should use a bit more complex identifier to replace with.

[dkamburov]

Also I tested it and seems like it's not working, I can't get "green" validated field.

I used grid-updates sample from the repo I only added editing and required field:

[deyvidnenchev]

getFieldKey can be deleted because it is not used anymore.