refactor: FileResolver should not handle URL parsing

[fvsch]

The responsibilities of the FileResolver class were a bit too wide. It should not be responsible for parsing URLs to extract a path. Instead it should only know about a root path, and get queries for local paths:

// before:
const { status, urlPath, file } = await resolver.find(url);

// after:
const urlPath = extractUrlPath(url);
const localPath = decodeURIComponent(urlPath);
const { status, file } = await resolver.find(localPath);