CB-10654 make hooks fire when platforms added from repo or dir

[tony--]

JIRA CB-10654 move hooksRunner.fire('before_platform_'...) till after platform has been resolved, pass resolved platform instead of target. move hooksRunner.fire('after_platform_'...) into platform loop, pass resolved platform instead of target.

[tony--]

I'd like to see this get fixed, so I thought I'd submit a PR, but I'm a node noob - this definitely needs to be reviewed before being merged in.

[tony--]

@bso-intel will you take a look, please?

[bso-intel]

It looks great assuming that before_platform_add and after_platform_add hooks could be platform specific. My understanding about the current convention is a little different, though. Thanks, Tony.