ENH: add suffixes arg to concat

[jreback]

xref #18347

the case for using add_suffix/add_prefix is either:

1. modify the column labels (can use .str.columns + ....
2. concat with annotation lables from there source frames (and not using a MultiIndex)

so this is an issue about adding support for 2., similar to the way pd.merge suffixes work.

[WillAyd]

See discussion in #29669 I don't think we actually want this