15beta1 tab completion of extension versions

Extension version strings need to be quoted. Either double or single
quotes will work. In released psql clients, tab completion offers double
quoted suggestions:

alter extension pg_trgm update TO <tab><tab>
"1.3" "1.4" "1.5" "1.6"

But commit 02b8048ba5 broke that, it now offers unquoted version strings
which if used as offered then lead to syntax errors.

The code change seems to have been intentional, but I don't think the
behavior change was intended. While the version string might not be an
identifier, it still needs to be treated as if it were one.
Putting pg_catalog.quote_ident back
into Query_for_list_of_available_extension_versions* fixes it, but might
not be the best way to fix it.

commit 02b8048ba5dc36238f3e7c3c58c5946220298d71 (HEAD, refs/bisect/bad)
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Date: Sun Jan 30 13:33:23 2022 -0500

psql: improve tab-complete's handling of variant SQL names.

Cheer,

Jeff