Add support for relative links (#1489)

This commit introduces several improvements to the file checking process and URI handling:

- Extract file checking logic into separate `Checker` structs (`FileChecker`, `WebsiteChecker`, `MailChecker`)
- Improve handling of relative and absolute file paths
- Enhance URI parsing and creation from file paths
- Refactor `create_request` function for better clarity and error handling

These changes provide better support for resolving relative links, handling different base URLs, and working with file paths.

Fixes #1296 and #1480

lychee-bin/src/formatters/response/color.rs

@@ -87,6 +87,12 @@ mod tests {
         }
     }
 
+    #[cfg(test)]
+    /// Helper function to strip ANSI color codes for tests
+    fn strip_ansi_codes(s: &str) -> String {
+        console::strip_ansi_codes(s).to_string()
+    }
+
     #[test]
     fn test_format_status() {
         let status = Status::Ok(StatusCode::OK);

lychee-bin/tests/cli.rs

@@ -972,7 +972,6 @@ mod cli {
 
         // Clean up
         fs::remove_file(&cache_file)?;
-
         Ok(())
     }