Move some methods from tcx.hir() to tcx

Renamings:
- find -> opt_hir_node
- get -> hir_node
- find_by_def_id -> opt_hir_node_by_def_id
- get_by_def_id -> hir_node_by_def_id

Fix rebase changes using removed methods

Use `tcx.hir_node_by_def_id()` whenever possible in compiler

Fix clippy errors

Fix compiler

Apply suggestions from code review

Co-authored-by: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>

Add FIXME for `tcx.hir()` returned type about its removal

Simplify with with `tcx.hir_node_by_def_id`

compiler/rustc_middle/src/middle/region.rs

@@ -180,7 +180,7 @@ impl Scope {
         };
         let span = tcx.hir().span(hir_id);
         if let ScopeData::Remainder(first_statement_index) = self.data {
-            if let Node::Block(blk) = tcx.hir().get(hir_id) {
+            if let Node::Block(blk) = tcx.hir_node(hir_id) {
                 // Want span for scope starting after the
                 // indexed statement and ending at end of
                 // `blk`; reuse span of `blk` and shift `lo`

compiler/rustc_middle/src/middle/stability.rs

@@ -219,7 +219,7 @@ fn late_report_deprecation(
     }
     let method_span = method_span.unwrap_or(span);
     tcx.struct_span_lint_hir(lint, hir_id, method_span, message, |diag| {
-        if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
+        if let hir::Node::Expr(_) = tcx.hir_node(hir_id) {
             let kind = tcx.def_descr(def_id);
             deprecation_suggestion(diag, kind, suggestion, method_span);
         }