Use new Intl formatter instances where applicable.

[skrustev]

Resolves #1155
Resolves #1904

Calendar:

• Replaced all instances of Intl.DateTimeFormat with ones from igniteui-i18n-core. No expected changes in behavior.

Combo:

• Validation strings should be available to set for it as well.

Date Input, Date Picker, Date Range Picker:

• Fixed default display format acting like input format and not taking into account locale zeroing.
• Replaced all instances of Intl used with the new date formatter from igniteui-i18n-core. No expected changes in behavior except for the first item in this list.
• Date Picker and Date Range Picker properly extend base Form validation resources. Setting custom resources through Input for now disabled.

[mddragnev]

@skrustev Kind of weird to me why the resources of the tree are on the item instead of the whole tree. Do we expect each item to handle its own locale and resoruces?

[skrustev]

@skrustev Kind of weird to me why the resources of the tree are on the item instead of the whole tree. Do we expect each item to handle its own locale and resoruces?

Yes at least that way the items don't need to be manually updated from the Tree itself and its the same way in Angular anyway.

[rkaraivanov]

LGTM with several comments, some of which are not related to this PR.
However, I do agree that it is strange to have the resource strings on each tree item instead of the parent tree element.