Grid Validation Implementation

[MayaKirova]

Closes #6501

TODO:

• Automation
• Changelog

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

[mddragnev]

On the tree grid add row sample, if you make the first two rows (with rowId 0 and 4) invalid. Afterwards if you call grid.validation.getInvalid() you will get an array with 2 invalid records. Then use the grid validation service clear method to clear only the validation errors of the first (grid.validation.clear(0)). Call again grid.validation.getInvalid() and observe that it returns empty array. This is because

 public clear(rowId?: any) {
        if (rowId) {
            this._validityStates.delete(rowId);
        } else {
            this._validityStates.clear();
        }
        this.updateStatus();
    }

the rowId is 0 and it is false. And the if block hits the else statement

[damyanpetev]

On the dev grid validation sample, if you make the first row invalid by one of the cells and then use the public row api to get the errors it returns undefined. grid.getRowByIndex(0).errors is undefined, if you use the public cell api, the error is there. So the formGroup seems to not persist the errors that any of the form controls have.

@damyanpetev should we collect both the errors from the formGroup and the child formControl's for the public row API, or should the row be associated only with the formGroup?

I think we should stick to what normal form groups do: the errors are specific to where the validation is - if there was a validator on the form group itself (cross-field), then I'd expect the row to have errors. Otherwise, the errors are under the specific cell and you can't really expose them on the row without changing the error type (since there would need to be indication for which field the error object is, which is a map of maps, essentially what row.cell.errors is already :) )

[MayaKirova]

@mddragnev Issues should be fixed now.

[mddragnev]

On the grid validation dev sample, when trying to add row make any of the cells invalid, the observe that grid.validation.getInvalid() does contain that row which is not added yet. If you cancel the adding, the validation service should not contain the invalid record for thar particular row, but it does.
NOTE: When canceling just editing it does work as expected

[damyanpetev]

That's a bit of a left over, can be fixed later though

[damyanpetev]

Still a few bits to clean up around ARIA and dev demos, but overall LGTM