Supporting changes for TISTUD-3814 Alloy: add hover info for element names in Alloy .xml file

- Move deprecated property up model type hierarchy to BaseElement
- Allow JSModelFormatter to take in BaseElements so we can pass in a TypeElement and get a somewhat decent hover.
- fix broken behavior due to changes for TISTUD-5648
- Add unit tests around BuildPathManager
- Make the BuildPathManager methods take in IBuildPathEntry, not impl
- Make the BuildPathManager methods return booleans rather than nothing