cli: add --quiet flag, enable logging by default

[kevinjqliu]

Great suggestion from @alamb to add a --quiet flag that suppresses all output, #220 (review)
--quiet sets the log level to ERROR so the CLI can still display error logs

I also took the opportunity to refactor the remaining usages of eprintln! and println!, replacing them with log statements.

We still retain the behavior implemented in #220; the cli still warns when skip generation

[alamb]

This looks great to me -- thank you @kevinjqliu !

I tried it out and it works great

(venv) andrewlamb@Andrews-MacBook-Pro-3:~/Software/tpchgen-rs$ cargo run --bin tpchgen-cli --release --  -s 0.1
    Finished `release` profile [optimized] target(s) in 0.18s
     Running `target/release/tpchgen-cli -s 0.1`
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./region.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./orders.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./part.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./customer.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./lineitem.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./nation.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./partsupp.tbl already exists, skipping generation
[2026-01-17T00:53:45Z WARN  tpchgen_cli::runner] ./supplier.tbl already exists, skipping generation
(venv) andrewlamb@Andrews-MacBook-Pro-3:~/Software/tpchgen-rs$ cargo run --bin tpchgen-cli --release -- --quiet  -s 0.1
    Finished `release` profile [optimized] target(s) in 0.06s
     Running `target/release/tpchgen-cli --quiet -s 0.1`
(venv) andrewlamb@Andrews-MacBook-Pro-3:~/Software/tpchgen-rs$

FYI @clflushopt