clo: Add orig_file_id and log_event_ix to search results.

[haiqi96]

References

Description

Current CLP's search results contain the original message, timestamp and original file path. However, the original file path is not sufficient to identify the file if multiple file shares the same path (if they are from different file system, or they are both rotated log with the same file name).

In this PR, we add file's original id and the log event index to every search result, which allows us to locate the specific file split that contains the matching result.

The change can be viewed as two smaller change:

1. We add a new member variable "log_event_ix" in the Message.hpp that tracks the index in the original file. The original "message_number" is renamed to "ix_in_split" to improve clarity.
2. We updated the add_results methods in the output handler to add log_event_ix and original_file_id to the search results output by clo executable.

Note that the new fields are not used in the code yet.

Validation performed

Built the package and compress a log file locally, Verified that

1. The results can be returned as normal by running search.sh
2. There's no issue when performing a search from webui.
3. Verifiy that extra fields are properly inserted into the results cache

[kirkrodrigues]

For the PR title, how about:

clo: Add orig_file_id and log_event_ix to search results.