Modifies bindings API to improve consistency

[dmikusa]

• Removes NewBindingsForLaunch
• Renames NewBindingsForBuild to NewBindings
• NewBindings is the recommended entrypoint for loading bindings across build/detect/launch
• NewBindingsFromPath is being left public for historical reasons and to provide a bit of extra flexiblity
• build.go and detect.go were switch to use NewBindings
• Uses os.ReadDir instead of filepath.Glob, the latter will swallow I/O errors which can make it hard to debug binding issues

Resolves #73.

Signed-off-by: Daniel Mikusa dmikusa@vmware.com