chore: Add tbl/csv subcommands, deprecate --format flag

[kevinjqliu]

Follow-up to #254.
Closes #173.

Adds tbl and csv subcommands alongside the existing parquet subcommand so every output format is a first-class subcommand. The top-level --format, --parquet-compression, and --parquet-row-group-bytes flags are deprecated (removal in v4.0.0).

Note that the default behavior remains unchanged. Running without --format and without a subcommand (e.g. tpchgen-cli -s 10) still defaults to TBL output, preserving backward compatibility.

Changes

New subcommands

• tpchgen-cli tbl — generates TBL (pipe-delimited) output
• tpchgen-cli csv — generates CSV output, with --delimiter option
• tpchgen-cli parquet — (already added in chore: Follow-up improvements to parquet subcommand CLI #254)

Deprecated flags (hidden from --help, warn on use, removed in v4.0.0)

• --format — use tbl, csv, or parquet subcommand instead
• --parquet-compression — use parquet --compression=...
• --parquet-row-group-bytes — use parquet --row-group-bytes=...
• --delimiter at top level — removed, move to csv subcommand; use tpchgen-cli csv --delimiter=... instead (we never released with --delimiter, so not a breaking change)

Bug fix

• Mixing top-level args with a subcommand (e.g. tpchgen-cli -s 10 parquet) now errors instead of silently ignoring the top-level args (args_conflicts_with_subcommands)

• csv --delimiter rejects non-ASCII characters at parse time (e.g. --delimiter='€') instead of failing mid-generation, since the underlying arrow-csv writer requires an ASCII byte

[kevinjqliu]

i thoroughly tested all the commands listed in this repo and all the error cases.

all commands ran successfully locally
all error cases are covered by integration tests

[clflushopt]

Left a couple on questions on how some args are unwraped prior to being checked via is_some() I think we should align that logic.

[kevinjqliu]

@clflushopt im pretty happy with these changes, lmk if you have any other feedback!

[kevinjqliu]

moving this forward, will fix forward if anything comes up 😄