time for pcre2 to be promoted to main?

[Jeremy Bicha]

Background
-----------------
pcre3 is the poorly-named old library. pcre2 is a new incompatible version.

2 years ago, vte and gnome-terminal upstream switched from pcre3 to
pcre2. The Foundations & Security teams did not like the idea of
having 2 pcre libraries in main, so the Desktop Team has been forced
to maintain extensive patches to keep gnome-terminal updated in
Ubuntu.

Since then, an increasing number of packages now support pcre2 and the
burden of keeping pcre2 out of main is affecting more Ubuntu teams and
developers. For instance, my understanding is that php7.3 (which will
be released in about 2 weeks) requires pcre2.

The situation with pcre2 is complicated because there are still large
number of projects in main that aren't working on switching to pcre2
so we will likely need to keep pcre3 in main for a while.

So I am opening a discussion about whether it is now time for pcre2 to
be promoted to main in addition to pcre3.

References
-----------------
https://launchpad.net/bugs/1636666
https://launchpad.net/bugs/1792544

Thanks,
Jeremy Bicha