* feat: initial load generator implementation
This adds a load generator as a new crate. Initially it only generates write load, but the scaffolding is there to add a query load generator to complement the write load tool.
This could have been added as a subcommand to the influxdb3 program, but I thought it best to have it separate for now.
It's fairly light on tests and error handling given its an internal tooling CLI. I've added only something very basic to test the line protocol generation and run the actual write command by hand.
I included pretty detailed instructions and some runnable examples.
* refactor: address PR feedback