Fix relative file imports from relative sources with the CLI viewer

Calling

    viewer ./examples/printerdemo/ui/printerdemo.60

would fail trying to resolve the relative path import "common.60" from
printerdemo.60, because we would apply the logic for resolving relative
include paths to be relative to the input file *also* for the initial
include path, derived from the main input file. That would result in a
search path

    ./examples/printerdemo/ui/./examples/printerdemo/ui

and that doesn't work :-)

So apply the resolution of relative include paths to be relative to the
input file only to those in the compiler configuration.

sixtyfps_compiler/typeloader.rs

@@ -321,17 +321,20 @@ impl<'a> TypeLoader<'a> {
         file_to_import: &str,
     ) -> Option<OpenFile> {
         // The directory of the current file is the first in the list of include directories.
-        let maybe_current_directory = referencing_file.and_then(|path| path.parent());
+        let maybe_current_directory =
+            referencing_file.and_then(|path| path.parent()).map(|p| p.to_path_buf());
         maybe_current_directory
+            .clone()
             .into_iter()
-            .chain(self.compiler_config.include_paths.iter().map(PathBuf::as_path))
-            .map(|include_path| {
-                if include_path.is_relative() && maybe_current_directory.is_some() {
-                    maybe_current_directory.unwrap().join(include_path)
-                } else {
-                    include_path.to_path_buf()
+            .chain(self.compiler_config.include_paths.iter().map(PathBuf::as_path).map({
+                |include_path| {
+                    if include_path.is_relative() && maybe_current_directory.as_ref().is_some() {
+                        maybe_current_directory.as_ref().unwrap().join(include_path)
+                    } else {
+                        include_path.to_path_buf()
+                    }
                 }
-            })
+            }))
             .find_map(|include_dir| include_dir.try_open(file_to_import))
             .or_else(|| self.builtin_library.and_then(|lib| lib.try_open(file_to_import)))
             .or_else(|| {