Support auto-imports (components and symbols)

[phoenix-ru]

To avoid extra overhead of using unimport in js side, most of the component and directive resolutions can happen in the Rust side.

• Research how unimport works on source code;
• Research how unimport gathers the auto-import symbols (across source code and dependencies);
• Research existing Node resolution libraries (import 'x' -> node_modules/path/to/x/index.js) in Rust;
• Ensure we can support Lazy prefixed imports;
• ... define other steps after research.