Add a benchmark for io.ascii with wide files that have thousands of columns

For example the issue solved by https://github.com/astropy/astropy/pull/10306.

See also https://github.com/astropy/astropy-notebooks/tree/master/io/ascii. I think that at least some of those made it into the benchmarks but not sure.

cc: @dhomeier

Review the existing io.ascii benchmarks and compare them with the astropy-notebooks/io/ascii examples referenced in the issue. Use astropy PR #10306 as context for the wide-file case, then add coverage for files with thousands of columns and verify that the benchmark records the intended performance scenario.

Written by the indexing model from the issue text.