Add tidy into ./x check

This commit adds src/tools/tidy into `./x check`. It enables rust-analyzer hightlights errors/warns on all codes in src/tools/tidy.
Since tidy is implicitly checked by `./x test tidy`, this new check is off by default.

Author: Shunpoco

src/bootstrap/src/core/build_steps/check.rs

@@ -841,3 +841,8 @@ tool_check_step!(BumpStage0 {
     mode: Mode::ToolBootstrap,
     default: false
 });
+
+// Tidy is implicitly checked when `./x test tidy` is executed
+// (if you set a pre-push hook, the command is called).
+// So this is mainly for people working on tidy.
+tool_check_step!(Tidy { path: "src/tools/tidy", mode: Mode::ToolBootstrap, default: false });

src/bootstrap/src/core/builder/mod.rs

@@ -1076,6 +1076,7 @@ impl<'a> Builder<'a> {
                 check::CoverageDump,
                 check::Linkchecker,
                 check::BumpStage0,
+                check::Tidy,
                 // This has special staging logic, it may run on stage 1 while others run on stage 0.
                 // It takes quite some time to build stage 1, so put this at the end.
                 //

src/ci/docker/host-x86_64/pr-check-1/Dockerfile

@@ -50,6 +50,7 @@ ENV SCRIPT \
     linkchecker \
     run-make-support \
     rustdoc-gui-test \
+    tidy \
     && \
   /scripts/check-default-config-profiles.sh && \
   python3 ../x.py build src/tools/build-manifest && \