parser.regex : key for all line

**Is your feature request related to a problem? Please describe.**
If you want split line with parser to séparate data (timestamp, service, ...) you lose the original line.

**Describe the solution you'd like**
It will be greate to define a kye like : Original_Key
If it's defined, when the line match, you can retrieve the original record.

**Describe alternatives you've considered**
The alternative is to have on parser with "^(?.*)$" and after another for split data.
However, this alternative solution is resource-intensive, as it requires every record to be parsed twice.

No files or tests are identified in the issue. Start by locating the parser.regex handling and its line-splitting path, then determine how a configured Original_Key could retain the input record during one parse. Done means matched records expose the original line under that key without requiring a second parser.

Written by the indexing model from the issue text.