Fixed: Incorrect selection of years on right side when clicking throu…

[schopchyts]

…gh years on shortcuts while contiguousCalendarMonths=false

Fixes #0000

Checklist

• Includes tests
• Update documentation

Changes proposed in this pull request:

Compare the entire dates and not only months

Reviewers should focus on:

Date range picker component

Screenshot

Before the fix:

After the fix:

[palantirtech]

Thanks for your interest in palantir/blueprint, @schopchyts! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[adidahiya]

thanks @schopchyts, code change looks good. could you please add a unit test to verify this behavior? probably in the describe("left/right calendar when not contiguous", ...) test suite