Enable bzlmod (#206)

Also upgrade Bazel to 7.1.0.

I have a follow up change that makes `fineGrainedHashExternalRepos`
works with bzlmod and this is a prerequisite to make the integration
test support bzlmod.

Unfortunately due to bazelbuild/bazel#21010
cquery mode is not working with Bazel 7 as for now.

Author: tgeng

.bazelversion

@@ -1 +1 @@
-6.4.0
+7.1.0

MODULE.bazel

@@ -4,3 +4,29 @@
 #
 # For more details, please check https://github.com/bazelbuild/bazel/issues/18958
 ###############################################################################
+
+bazel_dep(name = "bazel_skylib", version = "1.5.0")
+bazel_dep(name = "rules_proto", version = "6.0.0-rc2")
+bazel_dep(name = "rules_kotlin", version = "1.9.1")
+bazel_dep(name = "rules_jvm_external", version = "6.0")
+
+maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
+maven.install(
+    artifacts = [
+        "com.google.code.gson:gson:jar:2.9.0",
+        "com.google.guava:guava:31.1-jre",
+        "com.willowtreeapps.assertk:assertk-jvm:0.25",
+        "info.picocli:picocli:jar:4.6.3",
+        "io.insert-koin:koin-core-jvm:3.1.6",
+        "io.insert-koin:koin-test-junit4:3.1.6",
+        "junit:junit:4.13.2",
+        "org.apache.commons:commons-pool2:2.11.1",
+        "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.2",
+        "org.mockito.kotlin:mockito-kotlin:4.0.0",
+    ],
+    lock_file = "//:maven_install.json",
+)
+use_repo(
+    maven,
+    bazel_diff_maven = "maven",
+)