Typings Intaller initial work

[sheetalkamat]

This ports the typescript installer code from Strada

Instead of different process we use go routine to queue discovery of the packages install and then another go routine to do actual install.

Here are things that are still not ported and are todo for later

• Js file names to search typings for - need to exclude source files from external module search - currently this data is not threaded so left it for later
• custom npm path, safelist path etc that earlier we use to take - review and add the options that we really need
• Strada use to use events to notify client about typings installation. we need to use notification but will do that later
• TypingsInstaller currently uses "latest" as version to install typings for, to change this to correct version when we have typings for those published

While working on this, found out current bug in strada where typings already installed are not cached correctly if lockfile version is newer. This i havent fixed but will do that separately later. This means even if say @types/chai is already in our cache location installed, we will reinstall it. (Because package-lock.json structure change)