*: move util into pkg/util

Signed-off-by: Weizhen Wang <[email protected]>

server/err/BUILD.bazel

@@ -1,16 +1,5 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
-go_library(
-    name = "error",
-    srcs = ["error.go"],
-    importpath = "github.com/pingcap/tidb/server/error",
-    visibility = ["//visibility:public"],
-    deps = [
-        "//errno",
-        "//util/dbterror",
-    ],
-)
-
 go_library(
     name = "err",
     srcs = ["error.go"],