feat: improved results directory structure for load generation

[hiltontj]

Closes #24831

write and query load generation runners will now automatically setup files in a results directory, using a pre-defined structure. Users of the load tool can specify a results_dir to save these results, or the tool will pick a results folder in the current directory, by default.

Results will be saved in files using the following path convention:

<results_dir>/<s>/<c>/<write|query|system>_<time>.csv

• <results_dir>: the specified results_dir, or the results/ folder in the current directory
• <s>: spec name
• <c>: configuration name, specified by user with the config-name arg, or by default, will use the revision SHA of the running server
• <write|query|system>: which kind of results file
• <time>: a timestamp in the form YYYY-MM-DD-HH-MM

The resulting file structure will look like this:

results
├── one_mil
│  └── 270f721fd7
│     ├── query_2024-04-02-12-21.csv
│     ├── system_2024-04-02-12-21.csv
│     └── write_2024-04-02-12-19.csv
└── sample_spec
   ├── 270f721fd7
   │  └── write_2024-04-02-12-24.csv
   └── my-load-test
      └── write_2024-04-02-12-25.csv

The setup code was unified for both write and query commands, in preparation for the creation of a system stats file, as well as for the capability to run both query and write at the same time, however, those tasks remain for future PRs.

Other Changes

• Added /ping API support to the influxdb3_client::Client

[pauldix]

Great stuff 🚢

[pauldix]

TIL

[hiltontj]

@pauldix - I pushed up a commit that added some doc comments, but nothing functionally different, so once this is ✅ I will merge