Change generated IR output (--ir-out) from JSON to textproto.

This CL also cleans up all JSON formatting and conversion code in the frontend.

PiperOrigin-RevId: 951173343

Author: jasukej

rs_bindings_from_cc/BUILD

@@ -89,13 +89,15 @@ cc_library(
         ":generate_bindings_and_metadata",
         "//common:file_io",
         "//common:status_macros",
+        "//third_party/protobuf",
         "@abseil-cpp//absl/flags:parse",
         "@abseil-cpp//absl/status",
         "@abseil-cpp//absl/strings",
         "@abseil-cpp//absl/strings:string_view",
         "@abseil-cpp//absl/types:span",
         "@llvm-project//llvm:Support",
     ],
+    alwayslink = 1,
 )
 
 cc_library(
@@ -458,7 +460,6 @@ rust_library(
     ],
     deps = [
         ":ir",
-        ":json_from_cc",
         "//common:arc_anyhow",
         "//common:crubit_feature",
         "//common:ffi_types",
@@ -526,22 +527,6 @@ cc_library(
     ],
 )
 
-cc_library(
-    name = "json_from_cc",
-    testonly = 1,
-    srcs = ["json_from_cc.cc"],
-    deps = [
-        ":cc_ir",
-        ":ir_from_cc_dependency",
-        "//common:cc_ffi_types",
-        "@abseil-cpp//absl/container:flat_hash_set",
-        "@abseil-cpp//absl/status:statusor",
-        "@abseil-cpp//absl/strings:string_view",
-        "@llvm-project//llvm:Support",
-    ],
-    alwayslink = 1,
-)
-
 cc_library(
     name = "proto_from_cc",
     testonly = 1,

rs_bindings_from_cc/cmdline.cc

@@ -40,8 +40,8 @@ ABSL_FLAG(std::string, rs_out, "",
 ABSL_FLAG(std::string, cc_out, "",
           "output path for the C++ source file with bindings implementation");
 ABSL_FLAG(std::string, ir_out, "",
-          "(optional) output path for the JSON IR. If not present, the JSON IR "
-          "will not be dumped.");
+          "(optional) output path for the textproto IR. If not present, the "
+          "textproto IR will not be dumped.");
 ABSL_FLAG(std::string, crubit_support_path_format, "",
           "the format of `#include` for including Crubit C++ support library "
           "headers in the "