feat: expose internal date utils functions

[epr3]

Hello,

This PR exposes some of the functions used internally in the Calendar/Date Field components for creating months/years/decades, determining the types of DateValue objects and comparison functions.

These functions might prove useful for users who might want to build more complicated Calendar-type components and having these utilities might help with the manipulation of the placeholder/modelValue and/or building more complex Calendar grids.

[zernonia]

Thanks @epr3 ! I like the idea of exposing these utility. However I'm not sure we should expose it as a composable (useXXX). As the term use mostly ties with composable that utilize Vue reactivity, like how it does in VueUse.

I think for clarity sake we can rename useDateUtils to dateUtility.
or maybe we expose this utility as such radix-vue/date? WDYT?

[epr3]

Hello @zernonia,

Both variants sound very good for me.

Let me know what updates should I do to this PR.

[zernonia]

@epr3 I'm leaning toward radix-vue/date. This way all Dates related utility, types, function & composable can be moved there. Though it might have some breaking change as the import path will be different now, but since it is still in alpha tag, it should be quick and easy update for folks.

[epr3]

@zernonia Will add a new folder under packages/plugins and move everything Date related there.