[calendar] disabled month can be selected by navigating to a year at the edge of the enabled range

[samrichardsontylertech]

Describe the bug:

To Reproduce:
Steps to reproduce the behavior:

1. Create a <forge-calendar> instance with max date set to any month other than December
2. Go to December in a year earlier than the max date
3. Select the year of the max date
4. December of the max year will be selected even though it has no enabled dates

Expected behavior:
The calendar should select the closest month when it would otherwise select a month with no enabled dates.

Screenshots:

Please complete the following information:

• Forge version: v3.3.0
• I have searched existing issues before creating this report? Y
• Browser: All
• Platform: All
• OS: All

Additional context:
This may end up solved by the resolution to #545 if we decide to allow navigation to dates that can't be selected.