Add onClick handler to NavigationLink

[swese44]

we didn't want people to abuse links for clickable-only things, but there are many use cases (logging) where we need to handle a click and have the navigation. href is required, and we don't allow inline javascript or # there, so we shouldn't need to worry about abuse

[swese44]

@BrendanMcK do you see any issue adding this? otherwise clients need to add click handlers on divs/spans surrounding links to log an event, requiring role="button" etc. to pass tslint rules.

[BrendanMcK]

Maybe a better pattern is to have a LinkReporter component in the consuming framework that manages listening for these and logging them, and which has the appropriate tslint-ignore stuffs.

(There are plenty of valid reasons for having a click handler as an ancestor of an interactive element, so this tslint rule has potential for false positives.)

I'd be OK with adding this though; but would prefer is we could get a better name. onClick is too close to meaning "handle the interactivity pls". This is not the same as a Button's onClick. What we really want is something with a more passive name that indicates "btw, I'm going to navigate to the link you gave me, fyi" - ? - even handleLogging or similar might make the intent more clear.