Determine initial min-max value

[jackofdiamond5]

Closes #6494

When the time picker has minValue and maxValue properties set and is bound to a date object that does not satisfy them, it does not set the internal value and that later on causes the wrong text to be displayed in the editor.

So now we determine whether we should use the min or max value for the editor, based on the value that is received through the model and based on whether minValue and maxValue are set.

The same behaviour can be seen with a null value passed in to the model. Now the editor will not throw any errors if you have no value or if the value is not within the valid range. This also prevents it from displaying incorrect text.

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
• This PR includes API docs for newly added methods/properties
• 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
• This PR includes behavioral changes and the feature specification has been updated with them

[damyanpetev]

LGTM