Generate parameter pattern-match IR from pattern IR (#4388)

Also propagate the pattern IR along with the pattern-match IR, and use
it where appropriate.

Strictly speaking, some parts of the pattern-match IR are allocated
eagerly, while traversing the pattern's parse tree, but they still
aren't actually emitted until we traverse the associated pattern insts.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>

toolchain/check/handle_interface.cpp

@@ -60,8 +60,9 @@ static auto BuildInterfaceDecl(Context& context,
   SemIR::Interface interface_info = {name_context.MakeEntityWithParamsBase(
       name, interface_decl_id, /*is_extern=*/false,
       SemIR::LibraryNameId::Invalid)};
-  RequireGenericParamsOnType(context, interface_info.implicit_param_refs_id);
-  RequireGenericParamsOnType(context, interface_info.param_refs_id);
+  RequireGenericParamsOnType(context,
+                             interface_info.implicit_param_patterns_id);
+  RequireGenericParamsOnType(context, interface_info.param_patterns_id);
 
   // Check whether this is a redeclaration.
   auto existing_id = context.decl_name_stack().LookupOrAddName(
@@ -74,8 +75,9 @@ static auto BuildInterfaceDecl(Context& context,
       if (CheckRedeclParamsMatch(
               context,
               DeclParams(interface_decl_id, name.first_param_node_id,
-                         name.last_param_node_id, name.implicit_params_id,
-                         name.params_id),
+                         name.last_param_node_id,
+                         name.implicit_param_patterns_id,
+                         name.param_patterns_id),
               DeclParams(existing_interface))) {
         // TODO: This should be refactored a little, particularly for
         // prev_import_ir_id. See similar logic for classes and functions, which