feat: add cross-compilation support with --target flag

- Updated build and run commands to accept a --target option for specifying target platforms.
- Enhanced documentation to include cross-compilation usage and supported targets.
- Modified configuration to allow target-specific settings and toolchains.
- Introduced a new test command to run project tests with specified profiles and targets.
- Improved handling of target directories and output structure for different platforms.
- Added support for multiple targets in the configuration file.
- Implemented inheritance for workspace and dependencies based on target and profile.

src/core/config.rs

@@ -300,6 +300,7 @@ impl Config {
             "generated",
             "expect",
             "clean",
+            "targets",
         ] {
             if let Some(val) = table.get(key) {
                 let arr = val.as_array().ok_or_else(|| {