rhg: upgrade `clap` dependency
This one is the worst one to upgrade since v2 -> v4 broke a ton of API,
which thankfully seems saner now.
Contrary to what was done in the `hg-core/src/examples/nodemap` rewrite,
we're not switching from the "builder" pattern to the "derive" pattern,
since that would imply a much larger diff. It can be done incrementally.
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}