Add --total option to append a Total column to reports

[pascal-lc]

The standard report shows only blank, comment, and code counts per
language; there is no per-language total of all three. Add a --total
option that appends a Total column (blank + comment + code) to every
language/file row and to the SUM row.

• Applies to the text, Markdown, CSV, XML, YAML, and JSON reports.
• Works with --by-file, --by-file-by-lang, --by-percent (the Total
  column shows the raw line count), --3, and --sum-reports.
• combine_results tolerates the extra column, so --sum-reports works
  with reports generated with --total while remaining backward
  compatible with reports without the column.
• Ignored with --diff and --sql (documented in --help).
• Regression tests added in Unix/t/01_opts.t; full suite passes
  (678 language tests + 285 option tests).

[AlDanial]

It will be ~ 2 weeks before I can look at this.

[AlDanial]

I tested your code but am wondering what --total does that isn't already implemented with --fmt 2, --fmt 4, and --fmt 5. I will grant you that --total is easier to understand.

[pascal-lc]

I developed this against the cloc 1.96 package in Debian bookworm, which predates --fmt (v2.00, Feb 2024), so I missed that this already existed upstream -- my apologies for the overlap.

That said, --total also applies to the Markdown, CSV, XML, YAML, and JSON reports (--fmt is text-only) and is easier to use. If that's worth having, I'm happy to rework it; otherwise feel free to close this PR as a duplicate.

[AlDanial]

Good point on covering the formatted outputs. I need to figure out a clean way to merge your work in.