chore: restructure bazel macros

hack/bazel/js/proto.bzl

@@ -0,0 +1,36 @@
+load("//src/ts-protoc-gen/rules:index.bzl", "typescript_proto_library")
+load("@npm//@bazel/typescript:index.bzl", "ts_library")
+
+def _generalize_pb_imports(name, srcs = [], grpc = False):
+    suffix_match = "pb"
+    if grpc:
+        suffix_match = ""
+    native.genrule(
+        name = name,
+        srcs = srcs,
+        outs = ["index.ts"],
+        cmd = """
+           echo $(SRCS) | tr ' ' '\n' | grep '""" + suffix_match + """\\.js$$' | xargs -l1 -I '{}' basename {} .js | xargs -l1 -I'{}' echo 'export * from "./{}"' > $(location index.ts)
+        """,
+        output_to_bindir = True,
+    )
+
+def ts_proto(proto, name = "ts", grpc = False):
+    typescript_proto_library(
+        name = name + "_proto",
+        proto = proto,
+        visibility = ["//visibility:public"],
+    )
+
+    _generalize_pb_imports(
+        grpc = grpc,
+        name = name + "_proto_generalized",
+        srcs = [":" + name + "_proto"],
+    )
+
+    ts_library(
+        name = name,
+        srcs = [":" + name + "_proto_generalized"],
+        deps = [":" + name + "_proto"],
+        visibility = ["//visibility:public"],
+    )