Make VACUUM accept 1 and 0 as a boolean value.

Commit 41b54ba7 allowed existing VACUUM options to take a boolean
argument. It's documented that valid boolean values that VACUUM can
accept are true, false, on, off, 1, and 0. But previously the parser
failed to accept 1 and 0 as a boolean value in VACUUM syntax because
of a lack of NumericOnly clause for vac_analyze_option_arg in gram.y.

This commit adds such NumericOnly clause so that VACUUM options
can take also 1 and 0 as a boolean value.

Discussion: https://postgr.es/m/CAHGQGwGYg82A8UCQxZe7Zn9MnyUBGdyB=1CNpKF3jBny+RbyfA@mail.gmail.com