* Add full implemention of Map and Set to shims
* Update default Map interface
* Remove WeakMap/WeakSet
* Add tests for set shim
* Update most usages of Map<K, true> to Set
* PR Feedback
* Fix lint issues
* Change key in fsWatchCallback
* Simpler shim, more tests
* Fix typo in collection shim
* Handle undefined in indent helper
Telemetry shows that it's called with undefined (probably `stderr` in an
error scenario?).
* Add undefined to parameter type
* Check to make sure default npm exists at path before trying to use it
**Bug**
If the typings installer is run under a copy of node that does not include npm—but on a machine that does have npm installed—it will incorrectly try to use the npm that does not exist next to its running version of node
**Fix**
Make sure that we check that npm we select exists before trying to use it as the default. Otherwise, fall back to using plain old `npm`
* Add command line flag to gate new behavior
* Fix missing semicolon
