[9.x] Add missing onLastPage to CursorPaginator

[rodrigopedra]

Closes #42296

As stated on issue #42296 the docs on CursorPaginator's available methods states it has a onLastPage method, but the implementation of that method is missing on Illuminate\Pagination\CursorPaginator and its parent abstract class.

This PR:

• Adds the missing onLastPage implementation to Illuminate\Pagination\CursorPaginator
• Adds a test case covering both onLastPage and onFirstPage

Notes:

• Sent to 9.x and not 8.x, as the missing method is only on 9.x docs (see [8.x] Add missing onLastPage to CursorPaginator #42299 (comment))
• onLastPage implementation is borrowed from Illuminate\Pagination\AbstractPaginator