RFC 1005 does not respect XDG Base Directory Specification

[Fogapod]

XDG Base Directory Specification: https://specifications.freedesktop.org/basedir-spec/basedir-spec-0.6.html

~/.edgedb/projects folder structure is mentioned multiple times in RFC 1005: https://github.com/edgedb/rfcs/blob/master/text/1005-edgedb-project.rst

This is an inconvenience for me and many other Linux desktop users, there are too many apps that think they're special and should have a folder in home directory.

~/.edgedb should be a last resort folder in case $XDG_CONFIG_HOME is not defined.

This should be relatively easy to implement: checking additional set of env variables before writing/reading config files. I suggest making changes to RFC and implementations before 1.0.

related: geldata/gel-cli#308

[elprans]

We've had some discussions about this last year and the consensus was that it's simpler to have a consistent directory across all distros/OSes by default, mostly for the ease of documentation and troubleshooting. That said, we can consider using platform-specific paths again (FWIW, cargo seems to be moving in that direction as well: rust-lang/cargo#9178)

[elprans]

We've switched to XDG-conforming layout on Linux in Beta 3: https://www.edgedb.com/blog/edgedb-beta-3-ross#if-you-have-an-older-version-installed