String relativize(String scriptRef) {
		if (!Util.isRemoteRef(scriptRef) && !isValidCatalogReference(scriptRef)) {
			// If the scriptRef points to an existing file on the local filesystem
			// or it's obviously a path (but not an absolute path) we'll make it
			// relative to the location of the catalog we're adding the alias to.
			Path cwd = Util.getCwd();
			Path script = cwd.resolve(scriptRef).normalize();
			if (script.startsWith(cwd.normalize())) {
				scriptRef = cwd.relativize(script).toString();
			}
			String baseRef = getScriptBase();
			if (!Util.isAbsoluteRef(scriptRef)
					&& !Util.isRemoteRef(baseRef)
					&& (!isValidName(scriptRef) || Files.isRegularFile(script))) {
				Path base = Paths.get(baseRef);
				if (base.getRoot().equals(script.getRoot())) {
					scriptRef = base.relativize(script.toAbsolutePath()).normalize().toString();
				} else {
					scriptRef = script.toAbsolutePath().normalize().toString();
				}
			}
			if (!Util.isRemoteRef(baseRef)
					&& !isValidName(scriptRef)
					&& !Files.isRegularFile(script)) {
				throw new IllegalArgumentException("Source file not found: " + scriptRef);
			}
		}
		return scriptRef;
	}
Returns in all cases the absolute base reference that can be used to resolve
an Alias' script location. The result will either be a URL or an absolute
path.

@return A string to be used as the base for Alias script locations
src/main/java/dev/jbang/catalog/Catalog.java