Consolidated gpu calls into `data_harvester`.

Changed config flag from `enable_gpu_memory` to `enable_gpu`.

Added GPU utilization to the cpu widget.

Added GPU process memory usage and utilization percentage to the proc widget.
Added key binds for gpu process toggling.

Added GPU power usage to the battery widget.
Added bounds check to battery widget header.
Show battery widget header when `gpu_enable`.

Added feature flag `legacy-functions` to `nvml-wrapper`.

updated config file(s).
updated help text.
updated docs.

Remove GPU util from cpu widget
Remove GPU power from battery widget
Use reference for gpu widgets_to_harvest
Extract match arm to function for feature gate

…gpu-utils

…gpu-utils

adjust doc wordings
remove extra references
remove extra widget harvest checks
init proc gpu values
use convert_temp_unit for gpu temp