Create @intersystems-community/intersystems-servermanager NPM package

[gjsjohnmurray]

This PR adds an NPM package that other extensions can use when leveraging the API this extension publishes.

It also updates Server Manager to use this package, as a way of validating the package's correctness.

[gjsjohnmurray]

@isc-bsaviano this PR is a draft because it contains the part which defines the new package. Please take a look at the commit and raise any queries with me. Once you are happy with it I will build and publish the package, then add a second commit that makes Server Manager itself use the package. At that point I will set the PR as ready for review.

[isc-bsaviano]

Looks good to me

[gjsjohnmurray]

@isc-bsaviano this is ready for you, but there's no rush because I have already published the NPM package and started using it in another project.