Introduces telemetry for file create, read, and update operations.
This change adds the `gemini_cli.file.operation.count` metric, recorded by the `read-file`, `read-many-files`, and `write-file` tools.
The metric includes the following attributes:
- `operation` (string: `create`, `read`, `update`): The type of file operation.
- `lines` (optional, Int): Number of lines in the file.
- `mimetype` (optional, string): Mimetype of the file.
- `extension` (optional, string): File extension of the file.
Here is a stacked bar chart of file operations by extension (`js`, `ts`, `md`):
Here is a stacked bar chart of file operations by type (`create`, `read`, `update`):
#750
cc @allenhutchison as discussed
