RFC: expand $'' within heredocs

[Eric Cook <llua@xxxxxxx>]

Hey all,

bash 5.2[1] recently released and a change i found of interest is allowing $'' to be expanded
within heredocs. $'' is currently the only expansion that uses the `$' operator that doesn't
expand within heredocs(even $[] does); so i can see that edgecase being confusing in addition
to the feature just being useful.
cat <<eof
hello$'\t'world
eof
...


[1] https://lists.gnu.org/archive/html/help-bash/2022-09/msg00002.html
Not to bandwagon other shells, i just like the idea.