Add vector methods for numbers in `standalone-types-check.R` (Fixes #1714)

[khusmann]

In this PR:

• Updated Changelog
• Renamed check_number_decimal() to check_number() (at @lionel- 's suggestion)
• Added check_numeric() and check_numeric_whole(), vectorized versions of check_number() and check_number_whole()
• Added unit tests

Notes: The allow_na and allow_null logic is getting pretty repetitive (and error handling is not standardized). Let me know if you'd like me to submit another PR to abstract this across the check_*() functions. It's not trivial because of the differences across types, but I think I see a nice way to go about this.