[Chapel Merge] Drop official support for gcc 7 and 8

Branch: drop-gcc-7-8
Revision: fdb6331ed5cd11c167c04d5c692a2ad503cdff21
Author: jabraham17
Link: Drop official support for gcc 7 and 8 by jabraham17 · Pull Request #29523 · chapel-lang/chapel · GitHub
Log Message:
Drop official support for gcc 7 and 8

Drops support for gcc 7 and 8 as the host or target compiler for Chapel.

The only portability change for supported OSes is RHEL 8 now needs to install a newer GCC, I chose to put 10 in our docs but anything newer should work. I think GCC 9 might also work, but I see no reason to force the oldest version if newer ones also work

[Reviewed by @arifthpe]

Compare: Drop official support for gcc 7 and 8 by jabraham17 · Pull Request #29523 · chapel-lang/chapel · GitHub

Diff:
M doc/rst/usingchapel/prereqs-commands.rst
M doc/rst/usingchapel/prereqs.rst
M util/devel/test/portability/apptainer/current/almalinux-8-nollvm/image.def
M util/devel/test/portability/apptainer/current/almalinux-8/image.def
M util/devel/test/portability/apptainer/current/rockylinux-8-nollvm/image.def
M util/devel/test/portability/apptainer/current/rockylinux-8/image.def
M util/devel/test/portability/apptainer/extract-docs.py
A util/devel/test/portability/provision-scripts/dnf-deps-gcc-toolset-10.sh
A util/devel/test/portability/provision-scripts/dnf-gcc-toolset-10.sh
https://github.com/chapel-lang/chapel/pull/29523.diff