fix(cli): fix missing __init__.py in cli/handler package (#799)

* adding init file for cli/handler

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* imports fixed

* fix(cli): correct handler __init__.py exports and add license header

- Replace non-existent `build_cache` with `show_cache_path` to fix ImportError
- Add `show_cache_path` to `__all__`
- Add Apache 2.0 license header consistent with rest of package

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: bhimrazy <bhimrajyadav977@gmail.com>

Author: 3 people

src/litdata/cli/handler/__init__.py

@@ -0,0 +1,21 @@
+# Copyright The Lightning AI team.
+# 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.
+
+from litdata.cli.handler.cache import clear_cache, show_cache_path
+from litdata.cli.handler.optimize import optimize_dataset
+
+__all__ = [
+    "clear_cache",
+    "show_cache_path",
+    "optimize_dataset",
+]