public static URL makeURL(ProjectLocator projectLocator, String projectFilePath, String ref) {
		return makeURL(projectLocator.getLocation(), projectLocator.getName(), projectFilePath,
			ref);
	}
Create a URL which refers to a local Ghidra project with optional project file and ref
@param projectLocator local project locator
@param projectFilePath file path (e.g., /a/b/c, may be null)
@param ref location reference (may be null)
@return local Ghidra project URL
@throws IllegalArgumentException if invalid {@code projectFilePath} specified or if URL 
instantion fails.
Ghidra/Framework/Project/src/main/java/ghidra/framework/protocol/ghidra/GhidraURL.java