fix: Fix Safari 10–13 sticky regular expression quirks

[kitten]

Resolves #14

Summary

This resolves quirks that occur with Safari 10–13’s implementation of sticky regular expressions. It may not be a comprehensive fix, nor do I have an explanation for this.

The following regular expressions seem to match/test positively, when they shouldn't:

/null|true|false/y;
/(?:\.\d+)?(?:[eE][+-]?\d+)?/y;
/query|mutation|subscription/y;

The last one in this list actually doesn't, which further confuses me.
Either way, they can all be fixed by slightly rewriting them.

Set of changes

• Wrap constRe's pattern in a non-capturing group
• Wrap operationDefinitionRe's pattern in a non-capturing group
• Rewrite floatPartRe's pattern to strictly always be non-empty
• UNRELATED: Update word patterns to use \w more sparingly and accurately