Use roc_target over target_lexicon

Tailors a target class for our needs.
Replaces tons of uses across the entire compiler.
This is a base for later adding new targets like thumb.

crates/compiler/test_solve_helpers/src/lib.rs

@@ -79,7 +79,7 @@ pub fn run_load_and_infer<'a>(
             file_path,
             module_src,
             dir.path().to_path_buf(),
-            roc_target::TargetInfo::default_x86_64(),
+            roc_target::Target::LinuxX64,
             function_kind,
             roc_reporting::report::RenderTarget::Generic,
             RocCacheDir::Disallowed,