Enable support for MQTT Parser in stirling (#1756)

Summary: This PR adds the parser component of MQTT (v5), a newly added
protocol.

Related issues: #341

Type of change: /kind feature

Test Plan: Added tests

---------

Signed-off-by: Chinmay <chinmaysharma1020@gmail.com>

Author: ChinmayaSharma-hue

src/stirling/source_connectors/socket_tracer/protocols/mqtt/BUILD.bazel

@@ -0,0 +1,50 @@
+# Copyright 2018- The Pixie Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+load("//bazel:pl_build_system.bzl", "pl_cc_library", "pl_cc_test")
+
+package(default_visibility = ["//src/stirling:__subpackages__"])
+
+pl_cc_library(
+    name = "cc_library",
+    srcs = glob(
+        [
+            "*.cc",
+        ],
+        exclude = [
+            "**/*_test.cc",
+            "**/*_benchmark.cc",
+        ],
+    ),
+    hdrs = glob(
+        [
+            "*.h",
+        ],
+    ),
+    deps = [
+        "//src/common/json:cc_library",
+        "//src/stirling/source_connectors/socket_tracer/protocols/common:cc_library",
+        "//src/stirling/utils:cc_library",
+    ],
+)
+
+pl_cc_test(
+    name = "parse_test",
+    srcs = ["parse_test.cc"],
+    deps = [
+        ":cc_library",
+    ],
+)