Rename parse_node -> node_id (#3760)

This was previously discussed at
https://discord.com/channels/655572317891461132/655578254970716160/1209975051588210729.
I'm initiating this mainly because we typically use "id" suffixes to
indicate an `IdBase` being passed around and the non-id suffix of
`parse_node` suggests at it carrying more data than it actually does.
There used to be more reason for avoiding `node_id` because
`SemIR::InstId` used to be named `NodeId`, but that's no longer
necessary. As a consequence, I'd like to rename `parse_node` to more
precisely reflect its type.

In full, this is doing:

```
parse_node_kind -> node_kind
parse_node -> node_id
ParseNodeCategory -> NodeCategory
ParseNodeKind -> NodeKind
ParseNode -> NodeId
```

This is primarily in check and sem_ir, but with some `parse_node_kind`
references in parse too.

Pluralization is consistent with name forms on both sides, so that
wasn't part of my replacements.

toolchain/check/handle_if_expr.cpp

@@ -7,9 +7,9 @@
 
 namespace Carbon::Check {
 
-auto HandleIfExprIf(Context& context, Parse::IfExprIfId parse_node) -> bool {
-  // Alias parse_node for if/then/else consistency.
-  auto& if_node = parse_node;
+auto HandleIfExprIf(Context& context, Parse::IfExprIfId node_id) -> bool {
+  // Alias node_id for if/then/else consistency.
+  auto& if_node = node_id;
 
   auto cond_value_id = context.node_stack().PopExpr();
 
@@ -22,14 +22,13 @@ auto HandleIfExprIf(Context& context, Parse::IfExprIfId parse_node) -> bool {
   // Start emitting the `then` block.
   context.inst_block_stack().Pop();
   context.inst_block_stack().Push(then_block_id);
-  context.AddCurrentCodeBlockToFunction(parse_node);
+  context.AddCurrentCodeBlockToFunction(node_id);
 
   context.node_stack().Push(if_node, else_block_id);
   return true;
 }
 
-auto HandleIfExprThen(Context& context, Parse::IfExprThenId parse_node)
-    -> bool {
+auto HandleIfExprThen(Context& context, Parse::IfExprThenId node_id) -> bool {
   auto then_value_id = context.node_stack().PopExpr();
   auto else_block_id = context.node_stack().Peek<Parse::NodeKind::IfExprIf>();
 
@@ -38,21 +37,20 @@ auto HandleIfExprThen(Context& context, Parse::IfExprThenId parse_node)
 
   // Start emitting the `else` block.
   context.inst_block_stack().Push(else_block_id);
-  context.AddCurrentCodeBlockToFunction(parse_node);
+  context.AddCurrentCodeBlockToFunction(node_id);
 
-  context.node_stack().Push(parse_node, then_value_id);
+  context.node_stack().Push(node_id, then_value_id);
   return true;
 }
 
-auto HandleIfExprElse(Context& context, Parse::IfExprElseId parse_node)
-    -> bool {
-  // Alias parse_node for if/then/else consistency.
-  auto& else_node = parse_node;
+auto HandleIfExprElse(Context& context, Parse::IfExprElseId node_id) -> bool {
+  // Alias node_id for if/then/else consistency.
+  auto& else_node = node_id;
 
   auto else_value_id = context.node_stack().PopExpr();
   auto then_value_id = context.node_stack().Pop<Parse::NodeKind::IfExprThen>();
   auto [if_node, _] =
-      context.node_stack().PopWithParseNode<Parse::NodeKind::IfExprIf>();
+      context.node_stack().PopWithNodeId<Parse::NodeKind::IfExprIf>();
 
   // Convert the `else` value to the `then` value's type, and finish the `else`
   // block.
@@ -64,7 +62,7 @@ auto HandleIfExprElse(Context& context, Parse::IfExprElseId parse_node)
   // Create a resumption block and branches to it.
   auto chosen_value_id = context.AddConvergenceBlockWithArgAndPush(
       if_node, {else_value_id, then_value_id});
-  context.AddCurrentCodeBlockToFunction(parse_node);
+  context.AddCurrentCodeBlockToFunction(node_id);
 
   // Push the result value.
   context.node_stack().Push(else_node, chosen_value_id);