refactor: improve naming consistency in DataCombiner component

[raphaelchristi]

This PR improves the naming consistency in the data combination component by:

• Removing redundant "Merge" terminology since it's an operation type
• Renaming component to DataCombinerComponent for better clarity
• Converting operation enum values to uppercase
• Maintaining consistent terminology around "combine" vs "merge"

Changes:

• Renamed MergeOperation -> DataOperation
• Renamed MergeDataComponent -> DataCombinerComponent
• Changed enum values to uppercase (CONCATENATE, APPEND, etc)
• Updated method names for consistency (merge_data -> combine_data)
• Updated display names and documentation