apply the ABNF for path parameter names, OAS 3.2.0 §4.8.2

Header parameter names have already been adjusted.

The ABNF for the query component of URIs is at RFC3986 §3.4, but
percent-encoding is used, which allows for the use of any character.
Additionally, cookies using style=form are also percent-encoded and therefore
allow any character.

Moreover, cookie parameter names are percent-encoded when using style=form,
and even for style=cookie they are not used in serialization of objects when
explode=true, so a restriction on cookie parameter names is not added here;
however applications should apply their own restrictions, following the
"cookie-name" and "cookie-value" ABNFs at RFC6265 §4.1.1 (and ensure that all
disallowed characters are percent-encoded when using style=form).